There are plenty of downsides to Ryanair as to just about any outfit. The major upside is the probability of continued employment.
A friend of mine, on the inside, tells that contracts are for 5 years. Some of his colleagues refused to sign the latest version for a variety of reasons, one being it was unreasonable in their eyes, and so were no longer required. He tells there are rumours others, after the 5 year term, were not offered new contracts even though there is still fresh recruitment. If this is true your statement needs questioning.