When I was trying to decide between the 305 and the 405, I read every single review from a couple of different websites...it seemed that there was a lot of negative reviews on the 405, but also some hidden gems that make regular use of the watch a pleasure. I was shocked by how much Mac users seemed to hate the thing...since I own a Mac I knew I was going to have to work a bit harder to get the data to my Mac. For me, the deciding factor for the 405 ended up being the usability of the watch as an actual watch....it does look pretty sharp...and for $350 it better get more use than for an hour a day on a run...

Here is what I've seen with my own use over the last couple of weeks:
The set up on my Vista PC was actually pretty simple...I followed the directions to the letter and went to the[...] site which helped me get everything set up pretty quickly. There are some pretty good directions there...I can't see how anyone could screw this up honestly...but it seems that some folks have had trouble with it...I was able to update the firmware right then and that went well also (just be patient as it seems to update one firmware version at a time and not all at once)...

Once I got my PC all set up, I downloaded Trailrunner on my Mac...which supports the .tcx files of your runs that you can export out of the Garmin Training Center software (which really isn't good)...I don't know if there is a similar software package for the PC, but since I rarely use my PC, I really didn't take the time to look...

After I got done with some runs, I came home and was amazed at how easily the Ant+ stick picked up my watch...it even picked it up once when I left the watch downstairs...which I thought was pretty cool (but I haven't tried to see if I could do it again, I just bring my watch upstairs)...I would assume that if you have your watch in the same room as your computer it would pick it up pretty easily...

From this point I really wanted to get the data back on my Mac and into Trailrunner...and this seems to be the difficult part for most Mac users (the Garmin site says to get VMware and run it through that way-which is insane, but some might not have a PC box in their house like I do, so it would be the only way at this point)...What I end up doing is importing the data wirelessly, then pull it into Garmin Training Center...then export it as a .tcx file which I email to myself and pull up from my Mac...then save it to a folder and "open" into Trailrunner from there...sounds like a lot, but takes maybe 5 minutes at the most...and the newest version of Trailrunner is awesome...

I also have seen some reviews where the watch is not responsive to the bezel touching...what I ended up figuring out after watching the video on the Garmin site, is that when the watch is in powersave mode you actually have to wake it up before it will respond...which can be done by clicking either side button...then the bezel responds to touch etc...this is really a much cooler feature than you would think...it really helps avoid draining the battery during regular "watch" use...

As far as getting going on runs and using the HRM...it picks the HRM and Satellites up really quickly...which is surprising based on what I've seen in some reviews...it actually picked them up while I was in my house...and as of yet, I haven't had any trouble with using it on my runs...it shows my Heart Rate in huge numbers and the first screen shows pace/total time/total distance big enough that I can see it while on the move...I don't really need it to do much more than that as I am not what you would consider a fancy runner at this point with sprints or crazy heart rate work...I just have it auto-lap my time at a mile and call it good...

The GPS has been darn near 100% accurate so far (I live in Houston TX)...and everything that comes through on Trailrunner is also within 1%...

I took the advice of one of the reviewers and bought it from a running store in our area that is known for good customer service (Luke's Locker in Houston) and they have a 30 day no questions asked return policy that covered me in case anything crazy happened...I was nervous with all of the complaints about it not working when wet...but that hasn't happened to me yet (I even licked my fingers to see if anything strange would happen and nothing did)...

I really like the watch and would hope anyone considering it would really do their homework...I really like the watch and give it a huge thumbs up!

I have used this watch since August and at first I was really impressed.

Pros:

1. Awesome website to track progress.
2. Very motivating to see how you improve performance over time.

Cons:

1. You will have problems connecting to the Garmin website about every 6th time.
2. The GPS will not work about every 10th time - for some reason it has problems connecting to the Satelite
3. The GPS will not always be accurate

It is a start, but I believe this is version 1.0 for this style and I would wait for the next verson.

The touch sensitive bezel is the downfall of this watch.
it completely stops functioning when the slights bit damp/wet - like at the end of any workout. I've also had multiple experiences when not only the bezel is non-functional, but also the 2 buttons don't function when damp - which is surprising because these should be mechanical.
The Buttons are used among other things to stop/stop/lap and lock/unlock the bezel.
While running, the data is great HR monitor accurate and sensitive, pace and GPS functions just fine. The auto-lap feature is particularly useful. The configurable display fields are handy for different activities (I wore the watch on a bike trip and you can configure the display to show things like grade etc..). Multiple displays are handy , but you tend to configure one for each activity and leave it set to that display.
A Huge Huge downside is the lack of Mac compatibility. I purchased the watch in May, was told by the store that it was compatible. I found out later it wasn't and a Mac connectivity program was promised for November. The latest word is Jan 09 - it can't be that hard to do.
Battery life initially sucked - updated firmware have improved this - with the original firmware , I got 4 hours of GPS/HR function and then it died - in the middle of a Marathon.
knowing what I know now - I would not get this watch or recommend it - you don't want to worry about not being able to stop your watch or look at the results at the end of a workout.
The watch has also completely locked up on me - although now I know how to reset it - hold both buttons down for 6+ seconds and follow the instructions on the face.
for Mac users - until they come out with the Mac "ANT" software - you can't upload your data to your computer , or update the firmware , unless you borrow someone's PC or go to a Garmin store.

I would recommend buying the Garmin Forerunner 405 as long as you don't sweat when you run/bike/workout. However, if you are like me and sweat when you take part in these activities: DO NOT BUY THIS WATCH! Yeah, you'd think that Garmin would have tested their watch on actual runners, but apparently not. Once you start sweating the watch starts "freaking out." It beeps incessantly for no reason. You can no longer switch between the screens because it totally locks up. This is not an isolated incident either. I took my first Forerunner 405 back for the same reason and foolishly tried another one. Same result. Moreover, I'm not so sure it keeps very accurate distance. I've run on a number of marked trails and even tracks and the watch is always 5-10% off. At least the watch looks cool and works great when you are sitting on your couch. All in all I'm very disappointed in Garmin and wonder how they can look themselves in the mirror when they are charging $350 for a watch that doesn't work.

Unless willing to pay top $ for an unfinished product.

The list of issues I ran into:

1. The altitude and elevation gain/loss data is completely off. For example, once I ran an almost flat loop 7 times, yet the website shows that I have climbed 5,352 ft. during this run. That is impossible. Equally surprisingly, the elevation curve shows no pattern; I would have expected to see an elevation pattern repeating itself 7 times.

2. The Garmin Ant Agent application is in the habit of crashing on my computer from time to time. This uploads the data from the watch to the Connect website.

3. If the Garmin Ant Agent misses uploading one workout to the Connect site I can find no way to manually upload it from the watch. According to the documentation, one can force-upload all workouts, but I'm wondering if that will not overwrite the already uploaded ones.

4. The Pace and Lap Pace functions are so off that one must not rely on them. This means that you have no idea on how fast you're running.

5. One cannot press a key to manually record a lap (the Auto Lap/Lap Press Only function does not work).

6. The automatic lighting of the screen in response to key presses and alerts works only sporadically: it does not work for approximately one hour into the run. As I start my workouts before dusk, it means that I see no alerts while it is dark outside.

7. After I've upgraded the watch's software to version 2.3, I could no longer access the watch's second time zone: if I enable it from the settings, I stop seeing the first time zone.

8. The Connect website is amateurish and seems to be eternally "under construction". Is this mentioned anywhere in the marketing documentation?

9. If it rains, the bezel does not work: it does not take user input and flips screens randomly.

10. The support staff is totally unresponsive: I did fill out two complaints on the website and I have heard no response.

Please note that I did not use all the functions this watch offers, so chances are there are more bugs that I did not run into.