We fly Frontier all of the time and have never had a problem (knock on wood, as we're using them three times this summer...). I love saving money on flights! But as PP said, definitely price out everything on Frontier - seat assignments & luggage (including carry ons). One thing I like about paying separately for luggage is that we often don't each need one or two 50lb suitcases - we can do with 2 for the whole family.