You certainly need to know in advance how best to handle the Ryanair experience and how to prepare for a Ryanair flight. As long as you can get a bargain-basement fare on a route you want to travel (and don't check in luggage, exceed your cabin baggage allowance, or do anything else that incurs fees) and are prepared for the (often) far-out-of-town airports (don't forget to factor in the often considerable transport costs - and time - associated with this), and (mentally) prepared for the scramble for seats, the (lack of?) service, the total intransigence and inflexibility, etc, it's fine. There are lots of rules but they are well published and as long as you don't expect them to shown any leniency - i.e. don't put yourself in a position where you don't meet all their rules - then you will have no problem with them and can often get a good deal.
In all other cases - you're probably better off considering an alternate transport option!