An amazing course of general English (combined with individual lessons): everything is clear and decent. Teachers are professionals: at least according to the books, maximum was practiced in the conversation. With teachers I discussed modern news, films, show business people as examples were taken. It would seem that you don’t expect anything special from the standard course, but at least get effective and interesting preparation.
As for disadvantages, the price. If you want to study in London, prepare a lot of money. The high cost was leveled by a great location (everything is close, the central part of the city is very beautiful and modern), and if you look at the price on the individual lessons of London tutors, then there is a general benefit. The course can be found cheaper, but as for quality, OISE wins.