I found the interview much more informal than how the UK vet schools go about theirs, I interviewed at Bristol before and there was like mini-trials testing your maths, putting together weird objects in a set amount of time and then scenarios, followed by a really formal interview where they asked you indepth questions about the specifics of your work experience and they threw out a question on some big recent thing in veterinary, for instance my interview for Bristol was back in 2012 so I got a question on Badgers & TB. There was nothing like that in my UCD interview at all, it was like a more formal chat. It seemed like they want to get to know what kind of person you are, rather than the specifics of what you've learnt. I ended up way over preparing, I had a big speal ready to talk about my thesis and procedures I'd seen but I didn't need any of that. I got the feeling they want you to know a little bit about what you're getting yourself into - cost wise (we don't get student loans here so Irish drop outs due to money issues is a big problem in grad-entry) and syllabus/work load wise, so might be a good idea to go to the UCD website and get an idea of whats covered etc. Because it's usually a 5 year course here for undergrads they are squishing first two years into one, so it is intense and it would be good to show you are prepared for that.
Seemed like they want someone with a pretty open mind who hasn't sort of pigeon holed themselves into one aspect of veterinary quite yet, although its probably okay to have an idea but just that they want you to be open to learning about eg. equine even if you have no interest in that. I think be prepared to answer the general interview questions you'll get like where do you see yourself in 5 years, what to expect out of your career etc.
They definitely asked me a good bit about being able to deal with the pressure of vet school and being okay with not getting As the whole time. I think many north american students that come here are a bit shocked by the difference in grading. A's are only handed out for answers with exceptional extra reading/work, referencing etc. (obviously excluding MCQs here, most finals are essay based, midterms are MCQ). A correct but not comprehensive answer will get you a C, a slightly expanded one will get you a B but you don't get As without extra reading. They stress keeping yourself in good mental health and not killing yourself to get the 'A', and not giving up hope if you don't do well in one exam. That really comes across quite strong here as a whole, as only your final year exam grades count towards your final degree grade, so there's no point in killing yourself for the A in first year.
If there's any anomalies in your grades or application be prepared to talk about why they are there, the thing about UCD I love is that they take everything into account - it's not just about grades. For instance, the irish grad entrys take an extra exam called the GAMSAT to get in, and to be honest my score wasn't great at all. But I had a strong interview and work experience and they took that into account and here I am. So as long as you get your positive points across I think you'll do fine - they wouldn't have invited you for interview unless they were very interested.
As far as how I'm enjoying it, I absolutely love it here but I won't lie it's super intense. It seems like once mid terms start you are never more than a few weeks from an exam until end of semester, but I'm just not used to that coming from my last university where we were only examined at Summer. Our year coordinator bends over backwards to help us. There is lots of continuous assessment as you go along, which spreads out your work load so if you do bad at one exam it's not that big of a deal. They do expect you to do a lot of 'independent learning' in a lot of modules, and you have to go out and get animal handling skills yourself and all that but I think most of you coming from america have a good lot of that already, we're basically not allowed touch animals as work experience students here so we don't come in with much of any clinical skills such as injecting, taking blood etc. So you'll be in a good place as far as that goes compared to someone like me coming in from Ireland. There's also so much help from the upper years when you get here.
I'll end that essay here that's all I could think of. Sorry about the length! (Procrastinating final study...)