My uncle went there and I have visited,and am thinking about applying.
Large campus in ciy centre (10,000 full timers). Buildings date back 400 years. So unusual in having dreamy spires (the real stuff - not kitsch) with a good campus spirit and yet be right in the thick of a capital city. Also fees are just 750 euro for Europeans (£500) - for now!. Downside is that most courses are 4 years, and the marking is reputedly very tough - few leave with a first. There is a scholarship program at the end of the 2nd year, and if you get that, you get prime, free accommodation on campus for 2 years, which seems to be really something. Else in the first year (and that year only), you can reside in a leafy suburban dorm.
It appears a bit American in many respects... in some faculty, the 1st year is very general. So if you don't really know what you want to do, there is still time to choose. The 2nd year has lots of crossover subjects (like the philosophy of science). UK candidaes are a bit privileged as they give generous points for A-levels just to attract an international student body and in the interest of cross channel, cross border understanding etc (the Irish kids have to get As or thereabouts in six subjects, more searching of ability if you don't have I think!).
Closing date for the low the application fee is this weekend! Else apply later, but higher fee. No essays... just based on A LEVEL points www.cao.com and the website is very complete and explicit... www.tcd.ie www.ucd.ie is the competitor... (concrete suburban block but still good)... a bit like comparing a Warwick/York to an Imperial/LSE