If it helps, we usually have great experiences on Frontier. I think their good as long as your expectations are in check. First, their rates are usually very low, but they do charge for basically everything. So if you want a drink, even a coffee, it'll cost you. Same with carry on luggage! Some people hate that, but there are times they offer $60 flights from KC to Orlando, so I feel like I can pay $3 for a coffee.
The seats are fine for me, but my husband is tall and wishes there was more leg room. If you want, you can pay to upgrade your seat to one with more leg room and also get luggage included. I can't remember what the price of that is, but it is an option! My only complaint with Frontier is that they don't guarantee parents will sit next to their little kids. You have to pay for assigned seats to know you'll sit next to your own child. Me, I don't care what seat I sit in, but I don't want my 4 year old on the other end of the plane! I figure no one else wants that either, so I don't know why they charge.