I've been using the Garmin Edge 305 for a few weeks now.  The best thing about it is what you can do with the data once you've collected it.  I've been uploading my ride data to Motion Based. It's a very cool community of people adding gps data about all sorts of activities that they do.  This morning I noticed that sombody even added data for a ride in Iraq.  Looks an awful lot like the person was following the inside perimeter of a base or something.  One of the interesting functions on the site is that you can stage virtual races.  If two or more people ride the same route & upload their data, you can have a virtual race without having to be in the same place at the same time using the dot race function. Sort of like Tivo for racing.  Now I need to cut my travel back enough to ride more so I can challenge some friends to a good natured, trash talk-filled virtual race!

You can also download courses to your unit that you or others have done so you can see how you are doing compared to your virtual partner while you are riding.  Pretty neat stuff.

One thing that is missing from the Motion Based site is a way to interact with other people.  Say you see someone in the same area that rides at the same pace and you want to see if you can ride together?  I don't believe there's currently a way to do that.  I think it would be a good enhancement.

I'm still having problems with the heart rate monitor function as my unit is only capturing hear rate readings intermittently. There are other issues going on with this model too.   I'm going to have to contact Garmin's support soon to see if I need to RMA the unit if I can't get the HR function sorted out.