I needed a place to stay in London as I was relocating from the US to here. I found this to be an outstanding option for the price. What you get is essentially a room to sleep (with a small desk) and a nice bathroom - and a very nice shared area/kitchen with free breakfast food (you do the cooking and cleaning). It's like renting a room with a very nice shared area, and the wifi is free.
The downsides? Well, Tooting is Zone 3 and isn't in the tourist area - but for this price it's worth the trip up the tube line IMO. Also, the rooms are really one person rooms - the beds are small, so if you are traveling as a couple keep that in mind. Also, although not bad I think my bed wasn't super comfortable, but I slept well.
So, in short I would definitely recommend this place for someone in my situation - traveling alone to the UK and needing a place to land for a few nights.