I spent 2 nights there, on a solo trip. I'm 35, male. Pretty "accomodating" and not pretentious at all.
I was initially at a nearby little hotel with my partner, and having two more days to spend alone in London, just stepped in as it was very convenient.
Price: cheap, 12pounds/nite.
Location: very good, 5 min walking distance to Portobello Mkt, Tube (Circle and Central lines).
Many shops, restaurants (excellent Morocco one).
Quiet street, no night noises.
Free computer with internet access (a very old and slugghish one, but somewhat working).
5 levels, no lift.
Owfully kept: dirty bathrooms and common room.
Very, very poor facilities: 3 shared toilets + 2 showers for the Whole dorms/building (I guess around 30/50 guest when full?), and almost none working: water pressure/tank so low, there was no water at all for showers, as per my experience, 3 times out of 4 tries. Always people lined up outside the bathroom (to discoveer we couldn't use it...).
No breakfast (despite advertised at their website).
Common kitchen very dirty, I would not cook/keep anything there.
No credit cards accepted, cash only, advanced payment + not possible to see the room before payment.
I have visited many hostels in Europe and US, it's my preferred choice since I was interrailing as a teen. Even knowing in big cities (London first) one cannot expect great hostels, this one's by far the worst for me. In particular, I pretend to find at least a working bathroom!
I would never suggest this place, unless really the last possibility, and for no more than one or two nights stay.