I played around with WatchKit quite a lot, but I really have to say, that it's a huge step back, if you are used to all the nice features of UIKit. Animations and custom user interface items are quite hard to make and my biggest problem is that WatchKit does all the touch-handling for you. So it's not possible to make something like a square and drag it around with your finger on the screen (and that is what I need for my game, Elementary Minute).