Is StraightTalk as good as the major carriers?

If so, why is it cheaper? Is it a good idea to sign up for StraighTalk after getting an iPhone 5?

Straight Talk is cheaper because they do not allow you to stream music and videos on your phone. If you do stream music and videos on your phone it can be shut off because it violates Straight Talks terms and conditons.

Straight Talk will use AT&T or T-Mobile for service if you buy a Straight Talk sim card for service with the bring your own phone program.