I've loved going to The Electric Cinema for years. What the others say is 100% true, it really is the most luxurious cinematic experience in London. But after my last visit I decided there are some downsides, hence my 4* rating.
(i) nowadays they mostly show Hollywood blockbusters.. I miss the days of the more arty flicks
(ii) drinking wine with the film is great but as a result of most people consuming alcohol during the film, midway through you get half the cinema traipsing in and out of the loos
(iii) lack of popcorn (as previously stated) and finally
(iv) everytime I have been there the film starts late. This is really only an issue when you have dinner reservations after the film and forgot that they always run late.
However the fantastic leather arm chairs and foot stools; combined with a few glasses of chardonnay make this the best place to see a film in London!