Hi there,
It's a realy good place to stay. Smack in the middle of the old town.
It has a big kitchen, with the supply for cooking, free internet and tv.
Tube-station Gamla Stan is only 5 min walking.
Supermarket is nearby (you can ask the hostel for the location) and there is also a supermarket near Tube-station Slussen.
There are many pubs on the old town isle, but more or less trendy, not alternative.
Some more or less underground clubs:
Debaser
KGB bar
Helenes Krog (Wednesday= Baba Sonic Music Club)
There were some more clubs, but I’m not at home so can’t check the names for you:/
At the time I was there it was a bit IKEA-underground-style to me, but that’s very subjective ofcourse.
Think you’ll enjoy your stay there:)
Take care and good luck!
Andreas