Pros: 15% bonus if you top up with $100 and with any other amount during the same year; good coverage; allows roaming to Canada and abroad; reliable service
Cons: None
Summary: I've been a T-Mobile To Go customer for many years, and for me, it works great. I have a VoIP service as my primary phone, which is a perfect combination since I travel a lot and can take my VoIP with me on my laptop. I generally use my cell only for texting or emergency calls.
Customer service is reliable and generally helpful. Wait times are reasonable.
I was on Verizon before and have checked out many different carriers (including other prepaid services in the UK, Italy and Germany), and I have to say that T-Mobile stands out for its consistent ease of access, straightforward billing explanations (no hidden costs/fine print that requires a team of corporate lawyers to decipher) and generally no-hassle service.
I'm considering switching to another prepaid service, but only because my phone use is changing. I'd prefer to stay with T-Mobile but they are not (at this moment) the cheapest in the market, particularly for my kind of use (heavy text messaging, some calling).