Stayed two night at SoHostel and had a really great time. It was my first at a hostel and I slept at the 18-bed room. I was traveling alone.
It's a great place to meet new people if you're traveling by yourself, but you might take the initiative yourself.
In my opinion, the best with this hostel was the people who worked at the main rom (the heart of the hostel). There is a bar here with the opportunity to play beer-pong and karaoke and you can buy pizza. The workers was really great and tried to let people know each other and was making a good atmosphere.
The guys at the reception was not so friendly as the guys in the main room, but check in and check out was easy.
The downside with the staying is that there was a little noisy at night. But I think you must expect that in that kind of room, and that is difficult for the hostel to do much about.
The breakfast was just okay, you get what you need. It is also an opportunity to pay extra for the English breakfast.
The location was excellent, just beside Oxford Street and not far for Tottenham Court Station (the underground/tube).
I would definetly stay again if I was traveling by myself and wanted to be social and personal space isn't so important.