This is a very well run hostel, with some really friendly staff.
As soon as you book, you are sent a confirmation email with exact instructions in how to get there (plus the address in Chinese to give to taxi driver - very useful for westerners who can't speak the language!)
We stayed in a six bed dorm. It was average sized, clean and fairly modern. Each bed has its own reading light and plug socket. There is a heater in the room. No electric blankets, but the heater seemed to suffice (even in the dead of winter!) There are en suite bathrooms in each dorm - these are fairly small, but perfectly adequate. It can be a bit of a pain if everyone in the dorm wants to use the bathroom at the same time. The only communal bathroom is on the ground floor.
The hostel organises group activities every night (quiz, table tennis, hot pot night etc), though they didn't always seem to go ahead. I think that this may be because it was the low season and there wasn't a great deal of interest.
There are many tours available in Xian, and pretty much all of these can be booked here. They guarantee that none of the tours will dump you in a shop and hassle you to buy stuff (happens a lot in China!)
There is also a really nice roof garden. It was winter when we visited, so we didn't go up there much, but it looked like it would be pretty awesome in the summer.
A few minor gripes - they have a train station pick up service, but this is only from 12-2 in the afternoon. It's fine if your train arrives then, but if not, you're on your own (though it's not actually that far). They will also book train tickets for you, but this costs an additional 40RMB on top of the price. Whilst I understand that a booking fee is necessary, 40RMB is by far the most expensive we have encountered in China.
Wifi is available on every floor. It's very reliable, though tends to slow down at busy times.