I've played with my GPRS connection for a few days now. It really doesn't work very well at all, at least not here in Los Angeles or with my phone or with my usage. And yes, the phone is reporting decent coverage when GPRS doesn't quite work. Sometimes ssh works alright (with the ~1 second lag), but sadly it's not very consistent. Packet loss has occasionally been 20-30%, enough to combined with Other Factors make ssh not able to even initiate a connection.
So what about non-interactive connections? Web sometimes sorta almost works. Trying to sync my mail from the IMAP server (using Mail.app) takes Forever, and even then it'll only get the headers from a dozen new mails and not actually the mail content.
I might give it another try or two, but if it doesn't get much better then I'm definitely not keeping the service.
A comparison with AT&T edge makes it look like that might be marginally better. Reading another review doesn't exactly make me run out to try it. A third review makes it sound not quite as sucky. Oh, and the PC Card you need is Windows only so far, so it might as well not exist as far as I'm concerned. :-) And unlimited usage is $80/month. That's almost as much as I pay for DSL; not so attractive.
GSM World has more information than you ever wanted about GPRS and related technologies.
In unrelated news there's another Steve Jobs interview in Rolling Stone where he among other things talk about how the music industry works (and doesn't work). No making fun of Michael Dell dancing though...