I booked into this hostel initially for 3 nights..ended up staying for 7 :) travelling by myself wasn't a problem here; I met people within 10 minutes of being there in the huge eating/drinking area at the front of the hostel. I booked into a dorm (they don't have many, more twin/double/triple rooms) which consisted of 6 beds and 2 bathrooms, towels were included and for 30,000 kip /night ($3.50) I thought it was great value!
There were no keys for the dorm rooms which to some may be an issue but every bed is assigned a locker for valuables.
Downsides? You cannot book in advance. They have a 'pay as you go' system so you turn up and there may or may not be a bed..also breakfast isn't included but I can't grumble for that price :)