We took our first flight(s) with Frontier two weeks ago. We usually fly Southwest out of PHL or BWI. Both of those are around a 2.5hr drive for us. Frontier moved into Harrisburg this year, which is only about an hour drive for us. At $39 each way the savings (in time and money) for the 4 of us was substantial, even after paying to check 1 bag and select seats.
Our outbound flight was delayed about an hour due to the incoming plane being delayed while they tried to fix a bathroom on board. Our return flight was delayed about 2.5hr while they fixed the broken pilot's seat. I had emails with $25 travel vouchers waiting in my inbox when we landed.
They didn't announce a reason while we were waiting, so I was quite nervous about the flight potentially being cancelled. It was a rather full flight, and Frontier only flies into Harrisburg 3 days a week, 1 flight on each of those days. Such is the risk when flying the ultra low-cost carriers. I don't think I'd ever book Frontier with a connecting flight, or before a cruise. But for a last minute weekend getaway that we wouldn't have otherwise done due to driving time to a larger airport or higher cost at the local airport, it worked out well.
I didn't have any interaction with the employees at the gate, as there were enough people lined up to ask the same question over and over already (which they didn't have an answer for anyway). The flight attendants on both trips were good though, as was the pilot on the return leg that apologized for the delay due to his seat being broken. Apparently that is a safety issue.
To me the seats were no better or worse than economy seats on Southwest/Delta/United/American. Of course, I don't fit well in any of them and find them all uncomfortable. At least all but a few of the Frontier seats do not recline, so I don't end up with a seat-back jammed even more into my knees.