I think though that I have seen on some speedtest sites around 180 Kb/sec on ATT Edge. But that's about the best I've seen so far and in isolated places.

I was a Voicestream/Tmobile user for about 7 years and had 5000 anytime minutes for $39.95/month and was grandfathered in with that plan and left. Their Network was very seldom useful for me. I lived in a highly populated area and couldn't use the phone in my house or a ton of other places that ATT worked fine at. So I divested and never looked back. If Tmobile works good where you try to access it, then OK. But I traveled a lot and it was always dismal for the 7 years I was with them.

I knew when I bought the N900 that I would just have to put up with Edge. I'm glad I didn't switch for another reason though. I am so disappointed in the N900, I would be really pissed if I switched to Tmobile only to get pissed at the device. I don't think I need to go over what I am irritated with, there are a million threads that describe how I'm feeling. Nokia is a total let down yet AGAIN.

Ohh, and don't believe those TMobile coverage maps either... The coverage maps look like they don't cover much, and they don't cover near what they claim they do.

If you live in a very large city and don't have to travel a lot and use your phone between large cities it may work for you.

Wait... You already had AT&T? Call them up and change your plan down to the cheaper data plan! Tell them your new phone is no longer 3G capable and you just need edge. You can get the much cheaper data plan for non-3G phones easily that way. That's what I have.

Mine costs $15/month.

I was on AT&T and had a week or so left in my contract when I got my N900. I found it worked pretty well on edge, though web browsing was a bit slow. Even one day before the end of my contract, AT&T would have charged me hundreds of dollars to get out of it--no prorating. So I waited and used edge.

When the contract ended, I switched to T-Mobile and got the no-contract plan. All in all, cheaper than getting a new phone and contract with AT&T. Here in Austin T-Mobile is almost as good as AT&T was--a little worse on the coverage and I am occasionally dropping calls or failing to connect, neither of which happened on AT&T. My non-iPhone AT&T 3g coverage was actually very good for all of 2009.

In any case, you won't notice the difference on non-multimedia stuff. Stick to the mobile sites for big websites (e.g. touch.facebook.com or m.yahoo.com, etc.) and the performance is decent. And using apps such as facebrick and conversations for chat should be perfectly fine (facebrick wasn't out when I used edge, but it should be ok).