Doesn't deserve even 1 star.
Full fledged nickle & dime airline. Cheap tickets? Think again! They charge $35 for checked AND carry-on baggage. Extra money charged if you want to pick your seat. If you are flying with other people and don't pay the extra seat charge, they randomly assign you seats no where close to one another. $2 for a can of soda during the flight.
Don't bother buying tickets at the airport - I waited 3+ hours in line. 5-6 Allegiant staff members socialized while only one person was helping the 50+ people in line to buy tickets.
I did not encounter any good customer service from the purchase of the tickets to the return flight home.