I have had the Dash 3G for 6 or more weeks now and I love it. I know three other people with it and three out of four of us drop calls like crazy on this thing.
T-Mobile and HTC both deny any awareness of a problem with the device. I think this will change as more people realize that the dropped calls are inconsistent and can't be simply poor service area or loaded network.
I have been with T-Mobile now for 4 years and 6 out of the last 7 years. This is not a network problem, but a problem with this phone. Stay away.
I have done more research on the dropped call issue and am no longer sure if it is the actual phone or GSM 3G in general. There seem to be many reports that 3G phones (iPhones, Blackberrys, Android, and the like) drop calls because of switching issues with the 3G technology.
I don't know if my Dash 3G drops are more frequent than those reportedly caused by 3G switching because this is my first 3G Phone. Irritating none the less.