Ryanair don't have the most charming staff trained in good manners, the art of conversation, the correct way of serving a meal and other banalities that you get at some of the traditional or legacy airlines. Instead, you get crews who are given seemingly only practical training, many of whom have very poor levels of English and even poorer levels of customer service. This would sum up my experiences over the last two or three years with Ryanair.
We all know that Ryanair are not the best airline to work for, yet they are a vital stepping stone for many to begin working in the airline industry. As bmibaby.com mentioned, they have also been instrumental in completely turning the European airline industry upside down.
As long as the aircraft are safe, and they have to be to be JAA certified, then I'm quite happy to pay cheap fares for cheap service. After all, most of their flights are for less than three hours, so I'm sure most of us can live with it!