I stayed at ACYH for about a week, and it was in the best location. Few minutes walk to Pl. Catalunya, all the R1, R3, R4, L1 metro lines etc...Las Ramblas, etc... Prime location. Anytime I wanted to go out and do something, I just walked to Pl. Catalunya and took the bus/metro!
Friendly staff who are super helpful giving you travel tips. They can also offer to help you book tickets for certain things (museums and transportation etc...), and if you happen to go to Madrid like I did, they'll even tell you how to get there.
ACYH isn't some party hostel, which was perfect for me. I can party outside, so coming back to a quiet place was essential for me. The people staying here were super nice and quiet as well but I made friends with some folks that I could go explore with, too.
Amenities:
2 desktop computers with internet access.
They have a cabinet full of stuff you can purchase, like toothpaste, padlocks etc...
Free snacks and tea, but don't count on using this as sustenance :)
Refrigerator to store your stuff.
Laundry machines (and the staff can even help you do the laundry, for a fee).
The staff provide you with a ACYH card for which, upon showing to specific restaurants, you can get a 10% discount!
They have lockers where you can put your stuff (outside of the rooms in a hallway). They'll provide you a key and that's your ID basically for when you return to the hostel, unless of course they recognize you :)
Rooms:
I was in room 2, with 8 bunk beds. They provide sheets and pillow, and a small cubby where you can place your stuff. There are outlets on top of the cubby, so if you're charging your device, you'll just have to leave it there. There's also a small fan, but it didn't do much.
I stayed here in October, and one night it got pretty warm so I didn't use my sheets at all.
Facilities:
Returning to the hostel - so they don't give you a key or anything to access the building. You just have to press the green buttons and wait for them to buzz you in. I never had a problem, and they're quick to buzz you in!
The showers are clean but aren't super fancy, and you just have to deal with it. Personally it didn't bother me, but I can see others who are more "high-maintenance" wouldn't prefer it. The water goes off after about 20-30 seconds to conserve water, so just push the button in again every now and again.
Common room has nice seating area.
Kitchen has everything you need, pots, pans, hot water boiler, sink etc...
Summary -
Friendly, knowledgeable, helpful staff. Best location ever for a great price. Facilities are clean. I would definitely stay here again when I come back to Barcelona!!