Of course I do not claim that this will be better Facebook or E-mail client than Android or other smartphone. Anyway my wife is happy at what it does and most desired feature looks to be the incredible battery lifetime.
Yes, ot could work, but going from a 3.5'' hi-resolution screen to a 2'' lo-res poststamp is a severe degradation of user experience. I had to suffer like that for a week when changing the screen of my Streak, so I know the pain.
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In anticipation of TMO's obsolescence, and hoping to meet you all again: elsewhere on the interwebs, I am Dr Doppio.
It's got a proprietary Android locked-up OS but has a pretty decent PC interface that gives you almost full access to the file system. My wife got one free and she's happy with it. It seems to fulfill most of the items on your list. Of course if you just WANT to spend money there's a lot more options...
In anticipation of TMO's obsolescence, and hoping to meet you all again: elsewhere on the interwebs, I am Dr Doppio.