I've played wow for over 3 years.
I've used any number of addons that make my wow and raiding experiences easier, more fun, and just plain higher quality.
I've never messed with the basic stock UI (user interface).
In the past, I saw UIs that looked nice or organized things well, but I found it too much of a hassle to implement. Other addons could be dropped into the addon folder, but most UIs had to be added by also messing with other, scary folders like the wtf and settings folders.... don't make me do it! In addition, for some reason I never found one that looked just perfect for me, just like poor Goldilocks.
SpartanUI is a wonderful package of updates for the interface that (as you can see behind the cut)
curse and spartan packages is bartender with default SpartanUI settings. Installation of the newest version is a snap. I didn't have to mess with any other folders - so don't pay any attention to the youtube tutorials or online advice - just drop all the subfolders into the addon folder and away we go!
You'll have to redo most of your keybindings, but with bartender it's even easier than putting keybindings into the stock UI. The default bars are fairly small, which may bother some that are more prone to clicking. I tend to only click long cooldowns like army of the dead, so it's not a problem for me. I haven't used it in a raid yet, but I took it through a couple of heroics and while I'm not accustomed to where to look on screen for things yet, my keybindings kept me happy.
Now may well be a good time to think about updating your UI if you aren't happy with the stock one. Developers are making it easier to implement than ever before. Obviously, the stock UI works fine, but customizing can be fun, it clears up space so you don't feel like you're playing through a keyhole, and looks nice. But most importantly, your interface is another reflection of your preferences, playstyle, and 'gamer ID.'
Give UI customization a try!