Frontier is the better airline which ain't saying much...but in terms of reliability Frontier was leagues ahead of Spirit in my traveling experience.
Customer service was much better also, still poor no doubt, but far beyond Spirit.
Good deal for budget travelers.
It would help a lot if customers would lower their expectations...you bought the flight cause it was 15.00 yet you expect Delta level service...it ain't happening. Be glad with the price, sit down and stfu and let everybody get there safely and as quietly quickly as possible!