Quoted from CrazyLevi:
You'd have to be insane to fly Spirit. All I've ever heard are horror stories by people shocked that they have paid to make their own lives hell just to save 50 bucks by booking Spirit.
Don't do it.
I was nervous to do it, but I flew Spirit from Minneapolis to Chicago for Pinball Expo. Figured it was an hour flight, so why not, but I needed to be there by a certain time so I was worried about delays. I was very pleasantly surprised. I just walked on with no carry on as a friend had driven my bag to Chicago a day earlier. I knew about all the fees, so I made sure I needed nothing extra. Plane was actually early and only half full. Got there with plenty of time to get to the Stern Tour at Expo and it only cost me $37 total. The airport taxes and fees were actually more than the plane ticket itself ($19 vs $18). I don't think I would use Spirit if flying a long distance and I certainly wouldn't if I was flying with my family and a bunch of bags, but for this situation it was absolutely perfect and I would do it again under the same circumstances.