If you are looking for a hostel experience, this is fantastic! The location is amazing (in an old court-house and walking distance to king's cross and charles dicken's house) and I felt comfortable as soon as I walked in the door. Even had a great sleep in a full 12-bunk dorm thanks to the partially enclosed sturdy bunks. There were a lot of people but they're all fellow travellers and the hostel is so well organized i didn't mind the crowds. Wifi is only in common areas to keep bedrooms quiet.
I really enjoyed my stay at Robbin's Hall, although it doesn't feel like a hostel at all. Its really a dorm room out in the country. You get your own room with ensuite (great value), and the location is peaceful next to farmland and community gardens. Ponder's End is far away from London, you need a train. I'd go again for a retreat from the city or to write a book. Negatives- there is a kitchen but NO dishes or cooking supplies whatsoever - please, Robbins Hall, at least supply some basics!!
Best one-word description- seedy!! This is the worst I've seen in London yet- you can get much better quality for similar price elsewhere. Most of the 'hostellers' are people who actually live there and they were surly and uncouth. Its far on the tube, the building is very old and run-down, there was NO hot (or even warm) water in the shower and I was warned to watch my stuff and keep doors locked because of the other clientelle. Scary feeling. Free computer and a friendly bar-man were plusses.