I spent a while on the test realms yesterday checking out all of the new goodies in the 1.12 client. Some of these, like the new floating combat text feature, have come directly from popular community-created addons. I think, in may ways, I prefer the addons that are integrated game - that way, come patch day, the features I use regularly simply work, without need to tinker or download new code. However, custom addons provide a level of flexibility that's not present in Blizzard's own UI. With floating combat text, specifically, I may continue to use the original addon - Scrolling Combat Text - because I prefer being able to customize a little more than Blizzard's addition allows me to.
And what about all of you? Do you like to use addons - or even the sort that can't play when their addons aren't working right? Or do you prefer the low-maintenance of the default UI? And, whichever side you're on, do you like or dislike these new additions to the default UI?