I bought one last year and I tried it for a week.
It took a while to get the hang of it - if you pump it to much, not only do you run out of fluid very quickly but your bucket can fill up and then soak your leg as the fluid still goes onto the mop after you stop pumping.
It did work very well though but I stopped using it. It wasn't whether it worked or not that was the problem.
Firstly it was to heavy when full and to stop my bucket belt ending up around my knees I had to tighten the belt somewhat which was then uncomfortable to wear.
Secondly, I kept getting caught up in the tubing which is not good when at the top of a ladder and thirdly, the pump kept getting in the way.
Having written that, we do have a few jobs where I just do the mopping (all at ground level) and for that it is ideal.
I hope the above helps.