I stayed at Gusti for 1 night in August 2013 after attended a conference. Overall, it is a worth it hostel. It is very clean and the staff are very friendly and helpful. Here is the list of the (+) and (-):
Helpful and friendly staff
Personal locker is available (you need to bring your own lock)
Free breakfast (bread, jam, tea, coffee)
No lift. This can be a problem if you bring a big suitcase as there are only steep stairs available and the hostel is located on the 2nd and 3rd floors.
No bed curtain.
No personal power point.
The water heater in the bathroom didn't work at the time I stayed.
A bit expensive if you compared with other backpacker hostel with the same facilities.