depends which accomodation you get..
As with any university there are multiple blocks, which range in quality..
Overall, its a little pricey for what you get, but unfortunately that is what you get for being in London (even on the outskirts)
The ensuite accomodation is nice, very standard for universities, big kitchens, small pod-like bathrooms as most new university accomodation has - all very good and standard.. its expensive, but nothing out of the odinary..
Worth noting though, there are big differences between the blocks, so if you get to choose, then do your research
(Mill hall, for instance, has a pretty bad reputation, which is somewhat deserved.. lancaster accomodation has funny windows which are annoying and dont let enough light in... bishops is nice, isembard is also very nice, but mostly for post-grads, so pretty quite..) etc.
Non-ensuite accomodaton, is where I have spent most of my time
its reasonably priced, but you share 2 bathrooms for 10 people, and a very small kitchen. It looks a bit like a prison, but its very functional, and for me having the extra £20-25 a week, is worth sharing a bathroom + having a slightly smaller kitchen
Everything is on campus, which is very convenient and functional, whilst not overly pretty.
The accomodation off-campus is not so great, in my eyes.. Its very normal for university housing, shared houses - a range of quality.. but its all far higher priced then it should be. you would get identical houses in other cities around the country for fractions of the price, yet just because of it being within greater london, you will pay more. there is plenty of it around though, and its much more cosy then halls, for your 2nd/3rd year (though a lot of 3rd years go back to campus)