I have one. It's simple but not as natural and smooth in the handling as I did expect. You don't push the "button" down as one might think, you pull it and then flip the lever half way. It's easy just not the procedure you first think of when you look at it.
To fully release the plate after flipping the lever half you need to release the catch which is a little tricky the first few times. You need to press on the countersinked fluted/cogged axle and pull it in the outward direction. The axles diameter is a bit thin and the fluting do not give as much grip as I want. You can use your nail instead as it dont need any major force to move it in the direction. It would have been much better with a mm or two added to the diameter.
The ball head handling is exceptional. Super smooth friction, easy to lock and unlock, you can set a limiter which control the level of free swivel friction when unlocked. The production quality is outstanding and when tightened it feels welded into place.
I've noticed one thing though. After levelling it, unlocked, with its bubble. When you then tighten it the levelling change a tiny bit. Not much but still annoying.
Petter -Ever wondered where gadgets go when they die?