It's depending on which team you're in and which manager you have.
Pros
The pros are the usual the likes of a big player in the IT sector ranging from career choices to products and product training, stock options and well being choices. Canteen choices and the office are a big plus. Especially if you're a junior in the industry, it can be a career boost.
Cons
Genereal hire and fire attitude with no real strategy behind it. Currently they are in layoff mood, however this may change at some point. Being successful in your role does mean having to be in the right team and having the right manager. Be warned, not every manager is honest and not every team is really a team. Cost of housing/renting and food is considerably more expensive than even Paris or London, so if you're offered a salary and not familiar with the real cost of renting/living in Dublin you're likely to get very poor choices. New hires are likely to get better salaries than longer serving employees which causes friction in the team as loyalty is not rewarded. Promotion to higher roles often depends on who knows whom, and if one is Irish or not. Diversity and inclusion isn't their strongest suit.