7 Grandmasters is above average for an indie kung fu film, but it's still a pretty mediocre movie in every respect except the fight scenes. Story: sucks. Dialogue: sucks. Comedy: painful. Cinematography: passable. Sound effects: ridiculous (most are made by some guy blowing into a microphone). Sets: none. Costumes/makeup: bad. Acting: awful. Martial arts: excellent.
Yes, I'm sure it's the latter that earns the film its dubious "classic" status... there are a lot of fights, and they're well choreographed and performed (and occasionally well filmed and edited, though just as often not). But, that doesn't make 7 Grandmasters a good film, even if the fights do seem to make up 75% of it. In every other respect, the film is manifestly inferior to the Shaws productions of the time, and in even that respect it's still not as good as the films of the Golden Harvest renaissance that was beginning around that time.
If Kung Fu is really all you care about and you've seen all of Jackie and Sammo's better films already, then by all means check out 7 Grandmasters. If you're after a more rounded film experience, then add it to your wishlist somewhere underneath the 800 Shaw Brothers films Celestial has the rights to :)