In reply to lmarenzi: I'm quite familiar with it; in my humble opinion, still a very rudimentary tool, especially in the context of a good climbing gym, such as WW. I think the concept of training on a system wall still lags behind, in the UK and preference is often given to the fashionable campusing or finger boards. It looks cool to climb with feet in the air, kind of thing...
For a start the wall at WW is too steep (ideally it would be between 10-25 degrees or even adjustable)and most holds too small, putting off a lot of low-mid grades climbers(up to 7a,routes). Secondly the holds are not on the same level in a symmetrical pattern (probably a short-cut to use fewer holds, but it defeats the objective). Thirdly the sizes vary with the shapes (i.e. you don't have the same shape in different sizes, therefore you either don't hold it, hold it or find a certain type of hold too easy).
A system wall should assist a climber in the acquisition of strength whilst working on one's body coordination and movements, therefore advisable even at a relatively early stage and definitely well before resorting to campusing and finger-boarding, where one tends to neglect coordination and use of the feet. Therefore most types of holds should suit most climbers at most levels. But I'm sure we all like different things; happy climbing!