I booked at St Kilda but was moved to Victoria street, and so while I it was very apparent that this was a fortunate booking, I won't go into what the St Kilda one appeared, but I'd say to keep looking.
In regards to Victoria Street, it was crackhead central, you knew it by looking at it, and while my comfort zone wasn't breached, someone did leave after a single night. I'm not the easiest of people to spook, and for me the $30 a night to just sleep was good, and I wasn't concerned with the crowd 'down stairs'. The people I had a room with were decent, one guy was a little grouchy, but nothing bad. Some beds were enclosed on the top bunk, and were annoying to get in and especially out of. I had to jump down if there was no stool below me, not a high drop, just loud, occasionally. The beds themselves were...not exactly top notch, but this is $30 a night and crackhead central, so while they weren't the best and the one I ended up in 'after' the first couple of nights, was very squeaky to slight movements. I would however recommend you book Dr's appointment and /or an STD screening on your departure..Just in case.
Overall, for me it wasn't bad, but I'm able to also handle myself. If you're after cheap, I'd say keep looking, there are other places for the same price, just don't expect to be right inside the city. Though, from what I discovered, the city wasn't where the fun was, anyway.
P.S There aren't any lockers.