I used it when I was looking for someone to do my bathroom - had few offers and even arranged appointments to get the quotes. In the end, I didn't take any of them, but found someone else in ofri with great reviews - I got in touch directly and hired him to do the work...
...bottom line, it is reliable, but not more than any recommendation you could get from people you know if the number of reviews isn't significant.
I used this company
http://www.elite-trans.ch/ in the past for removal+cleaning... they did a good job and I got my deposit back without any deduction.