We did once. The experience was OK. They are primarily an airline that flies to major vacation spots and all we looked for from them was a ride to a better place. It worked for us with no problems. MUCH better than Spirit any day.
Brother in law is a pilot for a different airline and recommends them. They are more of a charter type airline. He said they have more leg room than your standard economy seat. If they fly out of your airport, I would give them a shot based on his recommendation. Full disclosure, I have not flown them personally.
We've flown with them once and re-booked with them for August out of DFW. The fares were cheaper than American both times. It's definitely more of a low-cost/Southwest-type of airline, but the crew was pleasant and we made it to CUN without issue. It seems to be hit or miss with people.
Considering their HQ is where we live (Minneapolis), and we can get a fairly good rate direct, I'm thinking that's what we'll do!
We've flown them several times out of MN including to Cancun. They're really decent and generally well priced.