My latest bike came with the XT dual controls and they are pretty easy to use.
I have the rapid rise derailleur and the difference is that you 'click' to change to and easier gear and 'pull' to get to a harder gear.
One of the problems with the dual controls is that it can be difficult to change while braking or, you can inadvertently shift while braking.
With rapid rise, this is less of a problem because you normally want to change to easier gears while breaking.
Personally I will change to individual shifters/brakes when I next can (probably when I get to change to SRAM)