...if your personal item is slightly too big. Yes, they charge more for even a hint of leg room, for some water, and in general they just really suck at customer service. Checked baggage fees essentially eliminate any kind of cost advantage.

But...Frontier works just fine for people who understand going into it that they're a crappy airline who don't really care if you have a good experience outside of a cheap flight. If you just want to get from point a to point b with a small backpack, then they're fine.