As far as I know it isn't common to rate on a 100 scale in Germany. 
My rating scale is a bit different (and rather strict).
The grades given are only approximations, as I generally don't use them, and when I write them down, it's meant as a comparison for people who also use them. As a generalization (though there are often exceptions) films with a rating above 50 are worth watching - below at your own risk.

higher than 100: don't ask...
98 - 100: A+
90 - 97: A
80 - 89: A-
75 - 79: B+
70 - 74: B
60 - 69: B-
56 - 59: C+
50 - 55: C

40 - 49: C-
30 - 39: D+
20 - 29: D-
10 - 19: F
00 - 09: don't ask...

B is on my scale a very good film, which is compulsively watchable. Films with a B (above 70) are imo worth owning! And I'd buy most of the stuff above 60 (B-).
Films above 80 are personal favorites.
So maybe I'm not that strict at all.