RyanAir and EasyJet are both great carriers for getting around Europe. Also, the price of the ticket is not static. As more tickets are sold and the date approaches, the fares go up. By the day of the flight, I wouldn't be surprised if it's up to $100/ticket. I've flown easyJet numerous times. Other than a couple delays, no complaints here. It is like Southwest in that you don't have assigned seats. You get a number upon check in and board according to numbers. Flight can't be too long.
Be sure and research. As mentioned before, they are often using rural airports and it can require some extra money getting to and from these airports. But, if it suits your needs, no reason to avoid them.
So, in short, they are fine but generally out of the way. Buy your tickets early as they only go up in price as the date approaches.