Flew on them for the first time in ages a few weeks ago. It was fine - rather like taking a bus.
You do have to play the game, and never trust a price until you get to the final screen. You need to expect zero flexibility, and zero contingency.
However, you get an OK seat and a pretty efficient operation (that has managed to get an impressive on-time rating given the quick turnarounds). Unlike easyJet (who still do the "please remain seated" routine while they prepare the flight), they know people will want to queue, and lay out cordons accordingly. Want to choose your seat? Queue or pay up for priority boarding.
When it works, it's fine - like I say, rather like taking a bus. Unremarkable.
When it goes wrong... Ah. Then you're on your own.