Nice hostel, great location to see the main sites, but pretty far off the sky train. They did make a mistake and put me in a mixed dorm, instead of female. The staff was really friendly and I'm sure they could have fixed it, but I ended up hitting it off with some of the people in my dorm, so it turned out great!
The Mad Monkey was the best hostel I stayed at my entire visit. Great atmosphere! It was really easy to meet people and the hostel staff was amazing. In the morning, they helped organize tours to the Killing Fields and S-21, so that I didn't have to hire my own tuk tuk.
Decent hostel, but don't buy the cheapest rooms. There isn't any AC in the single rooms, which is miserable with Siem Reap temperatures. The staff, however, was decently friendly. Definitely a better hostel for ex-pats and couples, not really big with the back packers. Still, nice place.