Carbonite is definitely a bit confusing to start using right off the bat
The best thing I can say is to carefully read the Options. There's alot hidden also. Each frame (Carb Minimap, Quest Tracker, etc etc) has a right click menu with some different options in addition to the standard Options Window.
The Authors have also packaged a nice little file in the Carb addons folder named CarboniteReadme.txt it's chock full of stuff to pore over.
And don't forget to take a look at the numerous post's in the Carbonite specific forum section here, many many stickies and alot of help to be had with near any issue.
As to the UI question, there's several compilations that may be similar to the workings of nUI. If it's the layout that doesn't fit your tastes, Id browse into the addon section here at WoWI and look over the Compilations that people have come up with. There's alot of nice work everywhere
The only thing to remember is that most Compilations are a collection of addons that someone found and setup to their (and potentially many others) liking. Through the course of browsing all those compilations, you may find you want to create your own too, which for many people is the best way.
Hope that helps you out a bit