Pros: Good price, good coverage
I'm pretty happy with T-Mobile. I've got a 300 minute plan for myself and a second for my wife for $30/month each. After taxes and everything, it comes out to around $74 per month for the two of us. We don't use the phone a whole lot, so I was just looking for a cheap plan without too many minutes, and T-Mobile had the best deal. I haven't had any problems with the coverage. In fact, I've been places where i have better coverage than my co-workers with different plans.
With the plan I got a free phone with bluetooth capability, and my wife got one with a camera. I was kind of hoping to get a phone with both features, but they're both pretty good.