Ben's place is a great place to stay in London. I would however only recommend this apartment for a couple as there is one small double bed and sleeping in the living room isn't that cosy. We were 3 friends travelling, leaving the 2 guys in one small bed and me in the living room.
The (brand new) air mattress is perfect but you have to move quite a bit of furniture to be able to sleep in the living room. It leaves you almost no room to move around or sit comfortably in one of the couches as it takes up almost all of the free space. The couch is really not that comfortable and a bit dirty.
You also have to keep in mind that the living room is really noisy. The apartment is located next to a very busy roundabout. I put in earplugs to sleep but they didn't block out all the traffic below.
All and all this is a great apartment, but I wouldn't recommend it for travelling friends.