I'm not much of a talker but I am an achievement ho somewhat so here goes... lol
I think vanilla MC is OK, but I like to have a reason to play a game other than to randomly collect hundreds of random Items and survive or pimp my house, etc. I think that FTB does that a bit better than vanilla MC. Granted there is still no real point to FTB unless you're playing the Pyramid maps or what not (very fun BTW, but only MC 1.2.5) but at least there is something to do with all the stuff you gather. On top of that, it makes a lot of otherwise mundane or boring things useful, such as lapis and the other random junk you get.
I also enjoy getting all the machines and other equipment running. I like to have factories running and making all my stuff for me. I'd like to eventually create a house that makes use of all the FTB stuff, cause I think it would be cool.
I do thin FTB has a few flaws though at this point. one being a lack of EE2. I love my item healing bags, unbreakable OP tools, and really cool end game OP items. That and now Mystcraft is a bit crazy in that you need to really go searching for all your pages. I kinda think I;m on the fence on that one though. I like the Idea of the search, but I don't really have the time to put in you know?
Anyway that’s all I got to say for now and Yay achievements... lol!