This was a bit of a mixed experience, and I would especially caution families with kids.
+ On the plus side, the group renting out was very professional -- prompt and clear in their communications. Also, they set us up with a very good taxi service to get back to the airport. So I have a lot of confidence recommending this group, which seems to rent out lots of places.
+ The location was really convenient - we walked everyplace!
- The really big negative was the noise. Perhaps it is just particularly noisy in Prague in July but there partying until after midnight every night we were there. (And I don't think the problem was just one noisy group.)
- Also, parents in particular should note that the loft doesn't have a high railing so you wouldn't want to have younger kids up there.