Meininger London, an English branch of a German chain of hostels, is a funny one. Nice location, in South Kensington; and nice rooms, facilities, and all that. But it's a bit weird, as hostels go. Doesn't seem to be much of a backpacker place: I guess the fact that they have a conference centre, and proper hotel rooms as well, contributes to this being the case. Plus, not much of a hangout area anywhere, which is a bit disappointing. Anyway, it's good if you want to stay somewhere nice for a short time, and if you're not too concerned about meeting fellow travellers or not.
Rooms: very clean, very quiet, and very secure. No complaints at all!
People: strange crowd for a hostel — lots of families, lots of tour groups, and even a few business people. More of a hotel crowd, really.
Staff: they stay behind the reception desk, they give you the keys (nice, reliable RF electronic keys, by the way), and that's about it.
Location: South Kensington — nice area, with everything you need around the corner, including a tube station.
Food: the breakfast is buffet, but not an amazingly appetising selection. Kind of a school canteen menu.
Internet: total ripoff, £3/hour. Go around the corner, there are places that offer it for £1/hour.
Hot water: very good. The bathrooms in general are very good here.