I am considering using these guys for a quick weekend trip next month. They are less expensive and I don't need to carry much but the reports of cancelled or late flights does concern me. Other airlines are just so ridiculously expensive right now!
They seem to charge not only baggage and carryon fees but also booking and passenger usage fees?
I did. That's how I found these other mysterious fees. They do add up.
I notice you are from the Frisco area. I too fly out of DFW. I flew Spirit to Orlando for the first time this past May, then flew them again for our Sept 1st-8th WDW trip. All four flights were fine. In fact, we arrived at MCO a few minutes early both times and also arrived back in Dallas a little early also. Now a few months before my May trip, my flight down to MCO got changed by several hours and the trip home changed by a little less than an hour, so I lost most of my first day down there and just a little of my last day. The Sept trip never did change more than a few minutes though, so was fine. Reading reviews about how crowded the seats were, I was a little concerned, so paid for the 'Big Front Seats' for the May trip. After looking at the other seats though, I decided they weren't that bad, so purchased regular seats in like Rows 5 or 6 for the Sept trip. They were fine and did not seem any smaller than seats I've had on Air Tran or American. If you go in knowing what your final fees are, Spirit is fine. Yes, I knew to carry my own drinks and snacks on and that I had to pay for my carry on and seat fee, but even with all the fees, Spirit was still ALOT cheaper than American, Delta, or Southwest for the times I was going (like $148.00 plus fees, compared to over $400.00 with all the other carriers that fly out of DFW or Dallas Lovefield). Again I flew Spirit for both my May and Sept trips and didn't have a problem either trip. I would definitely fly them if the price was right. For our upcoming Oct/Nov WDW trip we are flying Delta, but only because I caught them on sale late one night for $198.00 r/t. However, the Delta flight has layovers in Atlanta going down there and Memphis coming home, whereas the Spirit flights would have been direct/nonstop.
As far as being charged to print boarding passes as the airport: We had guest services at AKL try to print our boarding passes. They printed my mom's with no problem, but for some reason had a problem printing mine. Finally a manager type at AKL went into the back and "pulled some magic" as he called it and finally someway scanned me a boarding pass, but it was just a single one, not two on one page like my mom's. He said it should work though, since it had a bar code. When we checked our bag at the airport, I showed the Spirit GA the boarding passes and she said she did not know why mine printed out so funny, but I really needed the part the gate agent tears off, so she'd just print me another one. I was not charged anything and they were very, very nice.
That was rough enough but then I had to pay additional fees! I fought since they cancelled my flight and I had already paid for choosing seats tying to explain that we were traveling with our 2 children, one of whom is on the Autism spectrum. Was I supposed to let them sit with strangers? I was told that because it was considered a second flight, I had to pay. 
