As long as you accept the imdb ratings for what they are, they're fine; a lot of film fans would die a little inside when seeing some of the films the imdb members have voted up there at the expense of other classics, but it's easy to just not take it too seriously.
A current popular film with a fanbase will do well on the list regardless of whether it's actually pretty average - but that's fine, since the list is largely influenced by what's popular and talked about.
I mean, Christopher Nolan could make a 2 hour film of nothing but his pet dog wiping its arse continuously along the carpet and it would still get in the imdb250...
Just take anything on the list with a pinch of salt.
Also, many, erm more intelligent and considerate
people might look at the ratings but not rate a film themselves so again you might just be getting obsessed fans who want to big up or belittle a film just for the hell of it.