... especially compared to many.
When I *first* started playing (sometime in the middle of WotLK), the folks I was playing with badgered me into getting an addon to help with questing, completely ignoring the fact that learning how to find things (and how Blizz expected things to be found) was something that was valid in and of itself, not only in terms of me learning to maneuver and how to look at things (like, what the sparklies that meant 'pick this herb' looked like, vs sparklies from a spell) but learning the patterns/flow of the game. That said, when I ended up on a different machine, for a bit, and didn't have that, I definitely missed it. So, if you're going to get an addon, I'd recommend one that helps with questing, since that's really what you're doing most of at the start.
I definitely want to maintain as much continuity with 'plain ui' as I can, because I am frequently playing WoW on different machines (we have a pile of cheap linux boxes in my house, and I can be on any one of three machines...) and keeping them all in sync is a royal pain. So I tend to go for things that do one thing, and one thing well. I pull it down, set it up, and see if i notice it, use it, etc. If I do, I keep it - say, if I've put it on one machine, and when I'm on another I'm looking for it and missing it. And if not, I ditch it. (There was one 'all in one button' that had all the professions on buttons around it, and an open/close thing... I loved the idea, and never used it, as I'm much more a keyboard person than a mouse person, and always forgot to reach for the mouse to click the fancy button.)
At this point I'm up to 40+ addons, with a large stack backed up in my 'oh hey, this looks interesting' list. There are a couple that I only use sometimes - one that helps with the world-event achievements I only enable during world events, for instance - and others that I go nuts if they aren't installed. I'm on my ... fourth, I think, quest aid, the first one I was using failed for lack of data when Cata came out, and while the developer keeps posting that they're working on bringing it up to date, I've moved on to trying others and being somewhat more discriminating about what, exactly, I'm looking for. But, for the most part, I'm using the plain UI. I also don't raid, and only sometimes run dungeons, so I'm not really working in much data-dense situations.
One thing is certain - your experience *will* vary.
Have fun!
- Barleduq