I almost miss my flights on Frontier because they always seem to start boarding earlier than other airlines. This can be inconvenient but it can also be great to arrive at the destination earlier.
I did have some confusion on my last flight. I checked a carry-on bag at the gate but I forgot to provide my final destination to the flight attendant who also failed to ask. My bag almost continued with the plane into Indy even though I was going to Phoenix, but we were able to sort it out without losing a bag.
Comfort and amenities are a grade or two above Southwest, but Frontier does charge for checked baggage.