My only complaint is that I haven’t been able to get the VOIP features working yet, but I’m pretty sure that’s my fault, not the fault of the E90. Voice quality is great on T-Mobile, and (contrary to the complaint of the previous reviewer) email works great and can be synchronized down to every five minutes. I use both the regular email for my GMail account and the blackberry connect software for my corporate account, and they work without fail.

Battery life is better than I expected, and usability is excellent. One problem is the phone’s size… it’s a little bit of a brick, but you can’t have this much convergence without a small sacrifice of size. It’s much smaller and lighter than the previous combination of iPod Nano/cell phone/laptop that it replaced.
see detail spec here