The main difference, and I consider this to be a plus - the timing. Since med school here is still a 5 or 6 yr. undergrad degree vs. a four year course, things aren't so crammed. At Trinity, you take 2 years to do anatomy and neuroanatomy, instead of cramming everything into a year...or even worse...3 months. Physiology for me was spread out over 2 years, although it didn't quite make sense to do it that way and they've changed it to 1 year, but still...not as crammed. We have 3 clinical years instead of just 2, so theoretically, more practice and more patient exposure. I also consider that to be a plus, but will have to see if time is wasted due to inefficiency.
But for the most part, I think the main difference is that things are a little more spread out so it's not constant cramming. I think our breaks are longer too, which also accommodates the longer timespan for the course, although breaks get shorter as you become upperclassmen. This system allows you to actually have a life outside of med school for involvement in ECs (I row at a high level here, something I would not have been able to continue if I had gone to a US school), and also gives time to get a job during the summers to relieve the financial situation just a tiny bit and give some spending money. I got really lucky with the job I have, which is doing research and am now working on my 1st paper as 1st author - this is what I meant by having opportunities here. In the US, there just isn't time for all that.
In 2007, medicine will become a 4 yr. postgraduate degree here like it is in the US now. I'm not sure how this will change things, and it won't apply to me.
Oh, and I might get flamed for saying it, but a good difference is the people. In my class, we really work together. People email out their notes (!), and in general everyone tries to help everyone else. This definitely does not happen in the US at any school I can think of, no matter how nice the students are, because of the type of people entering US med schools. You know what I mean - classic Type A personalities. It is really refreshing not having to deal with that, although some classes aren't so lucky.
. The one con is that Irish schools in general aren't the most efficient, there's a bit of paper pushing and you never find things out when you want to...but if you can get around it and be more patient/laid back, it's alright.