Ryanair is confident that Europe's high-cost and often state-subsidized airlines will be no match for its low cost, no frills formula. In addition to our routes between Ireland and the UK, 15 European cities now enjoy the benefits of truly low cost air … see full wiki
Cons: really high charges to change flights, uses small airports
The Bottom Line: If you're not afraid of dodgy boarding passes...
For anyone who's ever flown on a nice airline like Virgin Atlantic, you have probably been impressed by all the "free" amenities they provide. When I flew from Boston to London on Virgin Atlantic, they gave us bag filled with a toothbrush and toothpaste, a sleeping mask, socks, lip balm, etc. We also got to watch the movie of our choice on the seat-back TV screens, play video games, and they fed us dinner including wine. It was nice, but it probably would have been nicer to have extra money! That's right, folks, all those "free gifts" are not really free. In fact, you are probably paying more for them than you realize.
On Ryanair, there are no frills. But if you are flying for a fairly short distance, you don't really need a lot of extras. The flight attendents come around and try to sell you drinks and snacks and various duty-free products such as perfume.
Ryanair has the most routes and the lowest prices of the budget airlines that have hubs in London (EasyJet, Buzz, Go...). Ryanair also has hubs in Shannon and Dublin, Glasgow, Brussels, and Frankfurt . I have flown Ryanair from London Stansted to Shannon and Venice and from Dublin and Pisa back to London. All four flights arrived basically on time and I successfully retrieved my luggage. I have had no problems with this airline so far (knock wood!) If you book far in advance (at least 2 or 3 weeks) and fly on a weekday, flights can be dirt cheap. My flight back from Pisa was around $20 plus taxes!
One problem with this airline is that it doesn't fly out of Heathrow. So, it can cost you as much as the flight to actually get to the airport! (Stansted Airport is 45 minutes by train from central London and it costs around £20 to get there and back.) But you still save money by flying on this budget airline as opposed to one of the luxury ones.
If you get to the airport allowing for enough time to check in as you are supposed to for international flights, you may have to wait around since Ryanair has a fairly small check-in time. Also, my "boarding pass" in Pisa was literally a printed out piece of paper with the Ryanair symbol on it and my last name written on it in pen! It was a little scary that they were THAT budget, but I survived! :)
However, you want to get there early enough so that you can sit with your companions on the flight. Ryanair does not assign seats. This can be a good thing or a bad thing depending on who you end up sitting next to. On our flight to Shannon, my friends and I got separated and I chose to sit next to the most handsome man on the plane (of course! Where else would I choose to sit?). But my friends ended up next to screaming babies or something. They are still bitter that I got to sit next to the hot guy-- even though he spent the whole flight trying to teach me Norwegian.
If you try to change your flight, Ryanair will charge you about the same price as your ticket as a fee. My friends and I missed a bus in Ireland so, in order to stick to our itinerary, we had to hitch a ride with a one-legged man who slaughtered Christmas geese for a living. Hey, it was better than paying £50 to get on a flight for the next day!