I did it.
In first year, you do a broad range of subjects, Math/Economics/Political Science/Business/Sociology, then in second year you start specialising. in second year I specialised in Political Science and Sociology, and then dropped Sociology going into 3rd year, so I did single honors Political Science in the end.
The hours are few, 2lecture hours per module per week, and then 1 hour tutorial per module every 2 weeks. Some of the classes are boring... but thats the lecturers fault more than anything. Trinity is the best university in Ireland so they have the best minds (doesn't mean they can teach). Saying that some of them are great!!!! Its quite a well respected degree in Ireland, so if you come out with a high 2.1 or 1st you should have options open to you, saying that, being a social science related degree most people end up going on to do a masters!!!
Trinity itself I think is great. StarsAreFixed is right when he says outsiders (UCD students) say its full of posh people but its not true, even doing BESS, an awful lot of people came from outside Dublin (or even England). There are tonnes of societies, and the SU is extremely active. Being in the centre of town offers its benefits too. Plus the grounds are gorgeous!!!
If you've any specific questions just PM me
P.S its not true that you don't have to specialise in any one subject - you need to specialise in at 2 at the most, so you can't take modules from all branches with you into 3rd year/4th Year. You don't get a BESS degree, you get a BA in whatever subject you specialise in ie BA Political Science, or BA Economics and Sociology