Experience with Ryanair?

If you plan on checking bags, say so during the booking process. It costs more to do it at the desk. Likewise, be SURE you fit the carryon requirements if you are planning to carryon -- if they require you to check it at the last minute it will be expensive, time-consuming, and you won't have with you what you need during the flight. Uncheck the box that adds travel insurance (last time I booked with them it was automatically checked). And unless you hold an EU passport you have to check in at the airport, not online.

Dale,

In my limited experience with RyanAir I've found them to be a reliable airline, although you'll have the feeling that you're "packed in like sardines" (I never would have believed they could fit that many passengers into a 737!).

One point to mention is that they're brutal with luggage limits. If you're even a bit over their free limit, you'll pay! That's also true of some of the other budget carriers, but RyanAir seems to be more inflexible than others in that regard. Their procedure for paying the over weight charge seemed a bit awkward too. After standing in one queue to check-in, I had to stand in another to pay the baggage charge, and then return to the first queue and wait again. I found it somewhat annoying.

I will use RyanAir again in future if necessary, but if there's an alternative with EasyJet or other carriers, I'll use them first if possible.

Happy travels!

Ryanair are introducing more stringent cabin baggage restrictions, so as others have said, read the booking conditions very carefully and make sure you understand them.
And as already mentioned, if you're checking any bags, do it when you make your reservation.
Having said that, I have flown then a few times now, and they have been very good.

I have found Ryanair to be a good reliable airline. They are extremely efficient and business like which leads to their profit margins. You will be bombarded with ads and charged for anything and everything beyond your initial seat and carry on.