I have been working with (NB not for) Ryanair for some months now, and I will add to the chorus of those who insist that their standards are very high.
There is a perfectly sound economic reason for this. It's the cheapest way to run an airline.
So far as maintenance is concerned, I have experience of many UK operators operating standards, from BAF in the old days to BA now. Ryanair is as good as or better than all of them, mostly better, in its adherence to the spirit and letter of the regulations, as well as in its corporate culture that "we must be best, because people expect us not to be".
Those who know BA well will spot the difference there.
It is also better than most if not all of the larger European and US operators;(including those that declare a policy of perfection, or whatever that is in German) not difficult in some cases, of course, but a high bar to get over in other.
I am less familiar with Ryanair's Flight Ops standards, but I have no doubt whatsoever that they are the same as maintenance, for the same reasons.
Pity about Ryanair's unnecessarily dreadful customer relations, customer service and website, but you can't have everything.