From an english lit point of view it's a great educational tool because you can study what the characters are like in themselves, but also through their relations with other people and the wider society of which they are a part. The characters are also well defined and relatable, and the themes, while interesting, are not subtable.
For that reason it's always been a key part of the GCSE curriculum.
Yep, I know I taught it. (But to younger students.) I just would like to see something else offered. On a plus note, my son will be sitting pretty for his Lit course. Before I knew it would be one of the books on the course, we watched the film and discussed it in depth.
On a film side, there was a fine television version made with Randy Quaid as George back in the early eighties.