You do need to read the conditions carefully as you go through the booking process though - print your boarding pass, check your bag weight and dimensions, arrive on time, check in on time, and you won't face any hidden charges.
During the flight they will try to sell you things almost non-stop, buy nothing a good pair of earphones doesn't solve.
They are known for carrying the absolute minimum fuel required, but this has only caused them an issue once in 2012 I believe.
And as said, they will land on time because they overestimate the flight time so they can say they're on time.
Frankly the biggest issues I have with them are their failure to recognise any trade unions for any of their staff, they force some pilots to register companies in Ireland to avoid tax, and their previously sexist advertising. Another example of a company not valuing employees and doing everything it can to avoid tax.