i lived in astor college 2 years ago and thought i'd chime in...
while astor may be a bit older than the gower street/campbell house rooms, it makes up for it in its location. charlotte street is easily the best place to live in london. its not significantly farther than the other halls to ssees, and its a lot more convenient. you have 3 supermarkets (sainsburys, tesco, m&s) within a few minutes walking distance, as well as 3 tube stations (goodge street, warren street, great portland street). charlotte street itself is lined with pubs and restaurants of varying prices. oxford street is a 5 min walk away, and i could walk to much of the west end in 20 minutes. it saved on transportation costs! but, the area (fitzrovia) is off the tourist path, so its a bit less crowded than, say, soho.
any frustrations i had with astor were made up by charlotte street. i doubt i'll ever get to live in a place that great again! my recommendations: the fitzroy tavern, icco pizza place, italia uno, thai metro and of course NEEL AKASH. its my favorite indian place in london and also run by the friendliest staff possible. we always got a 10% student discount, and usually free popadoms or even a free bottle of wine. gotta love it.