For one the plastic casing was as cheap as you can get. I dropped my phone once while getting out of my car less then a foot off the ground and the thing looked like I threw it against the wall.

Second the gps did not work, this was not an uncommon issue, so uncommon that T-Mobile replaced my phone no questions asked for a G2.

Third the software they put on the phone, while not an issue for this phone, was slow, buggy and hard crashed my phone at least once a week. This coming from the G1, running community build roms, which hard crashed maybe twice in the 2 years I owned it.