There still are a lot of bumps. Their billing systems remain a mess, especially trying to use it on an iPad (if I don't disable wi-fi, it asks me for the iPad's phone number). I really wanted to use T-Mobile to support their free 200mb offer, but it's a mess to sign-up for extra data.

My final reason for leaving -- even though they suffered many high profile password hacks in the past, they still store them as clear-text and email it to you when doing a password reset.