Just flew to San Diego direct from DSM. Service in the terminal and on the plane was fine, similar level to what we expected given what we paid. Prices are so low because you can pick and choose what you want for services, down to small details - they’ll even have things like charging $10 for a printed boarding pass at the airport, we downloaded the digital ones and had no issues, so there is another part of your traditional ticket price that’s not included. If you don’t care where you sit and take very little with you for baggage, it can be insanely cheap. The cost for various fees isn’t bad, though. We paid a bit extra for more legroom, checked bag, and boarding early and it still was significantly cheaper than any other airline would have been.
Drawbacks - because Allegiant doesn’t always employ enough crew at airports, you can get stuck for 20-30 minutes waiting to be towed to your gate like we were after landing in DSM. They try and schedule lots of departures or arrivals during limited windows of time so they don’t have to pay for staffing at all hours of the day. Also, there is no internet access or any in-flight entertainment - bring your own device w/headphones or a good book. Overall, we’d use them again as there is nothing that was particularly bad about the experience, and you can’t beat a nonstop flight. It’s expensive to fly on any airline, which is why we rarely do it, but companies like Allegiant make it possible for us to go places we wouldn’t otherwise be able to afford.