This is a great hostel! Super new and super clean, located within walking distance of the CBD and all methods of public transport. The hostel had a friendly feel and staff were lovely. The room was very nice, the beds were about as private as bunk beds could be and there was an en-suite bathroom with shower, as well as plenty of wall plug sockets by the beds and throughout the rooms.
Be aware that there is no real kitchen at this hostel to do your own cooking, there is a casual restaurant with fairly reasonable prices.
They also have a luggage room in case your flight/transport out of Perth is later than check out.
I stayed in winter so off-peak, but was not disturbed by any noise at night.