I don't have anything bad to say about this controller really. It speeds up your workflow instantly. It took me about half an hour before I figured out how to set it up in Totalmix FX (thanks to the RME youtube channel), but once I had that going, it's easy.
Sizewise it's big enough so you can control it from out of the corner of your eye, very tactile, but small enough as to not take a lot of space on crammed desktops. It's lightweight, built like a Land Rover and works on USB-1 so hardly any CPU-draw. The ability to work with snapshots is a great feature to easily swap between a mixing, tracking or mastering environment.
The big volume control is definitely a plus.