They have newish planes that are already horribly shabby (torn seats, worn carpets). They don't clean the plane between flights. There is very little legroom. They provide zero food/beverages on even 5+ hour flights without a large cost. They overbook. They charge for every piece of luggage. No video screens or audio system in the plane. Very little carry-on space.

I have heard great things about RyanAir, they just tack on the charges after you take off for every service.