Generator London is an enormous place: with over 800 beds, it's the biggest hostel in Britain. It's also in a great location, and it's very cheap (rock bottom for London prices, at least). However, this comes at a cost. Its enormity combines with its weird punk-industrial decor, to make it feel a bit like a prison. The sheer size of the place attracts homeless people: and security guards actually patrol the inside of the hostel, and randomly ask guests to show their room keys, as proof that they're staying there (such a nice, friendly touch, that is). The bar, dining room, and chill-out rooms are nice; but since most people come here in groups, and since it's just so big, socialising is hard. Basically, the Generator feels like a totally last-resort place to stay in London: I'm not planning on getting stuck here again.
Rooms: reasonably clean, but dark and crowded, and the air-conditioning systems also make them really noisy at night (and do nothing to keep them warm).
People: although most people are regular backpackers or young vacationers, they're not the most friendly bunch, and the environment doesn't make them any friendlier. There are also quite a few weird non-hostel types here, such as families and random old men.
Staff: 24-hour service at reception, but they're just doing their job, nothing more. Service at this place is about quantity, not quality. Their mere expressions say it all: "you get what you pay for".
Location: central London, between Russell Square and King's Cross tube stations (giving easy access to all major city sights). British Museum is in walking distance.
Food: the free breakfast doesn't taste very good (the milk in particular is pretty dodgy, probably skim or something), but at least it's all-you-can-eat. They have dinner every night (extra charge), but I wasn't game to try it — I suspect it's equally prison-food-ish.
Internet: available at any of about 10 terminals in the dining and chill-out rooms, for £1.50/hr. They have it cheaper across the road.
Hot water: quite good, although the bathrooms feel like a robotic laboratory.