The next funnest thing is BG tanking, and the best way to be a BG tank, is to roll a healer.
I don't use any UI addons at all. Well I do have one that shows enemy names for RBG's which I just started (literally 1L-2W is my RBG record). My group said it was required or I couldn't play with them, so, whatever.
I've healed, DPS'd, & tanked in raids from Vanilla to Wrath, and the only time I used an addon other than something like recount, was vanilla on my hunter. Cause having your ranged weapon automatically broken really sucked if you lagged a little bit and weren't fast enough to bag it.
But then again my guild wasn't about "progession" it was going through the content at a leisurely pace. We didn't kill LK till near the end of the expansion, when the buff was up to something like 30%, and we were fine with that.
Anyway, I have no problem with the base UI for healing. I'd say now, it is far and away better than it used to be. Vanilla/BC it sucked, wrath it got pretty good. I'd say it's pretty polished now, for what it's supposed to be.