I switched to Sprint myself and I'm not completely dissatisfied. I don't get LTE and their 3G is not as fast as I experienced with AT&T or Verizon (about half as fast), but it's comparable to slow DSL. Not dial up.
Their coverage is great (actually better than AT&T). I just keep reminding myself, it's a phone. I don't need 10+mbps. It'd be nice, but I can do everything I need on a phone with the speeds I get.
However, I am hopeful we'll get LTE soon. ~$70 a month (with corporate discount) for unlimited data, text and free calls to any mobile (free nights and weekends) would be an amazing bargain compared to Verizon and AT&T, who would charge a minimum of $100 for a comparable plan.