I'm not saying famitsu has no value but they grade too many mediocre games too high and some good games get too low. For example motorstorm got a 30, the same score as Sonic on 360. Mario strikers on gamecube got a 27, that horrible gundam game on PS3 (not Musou, the first one) got a 32.
I dont' think that famitsu scores affect sales almost at all.
currently playing: Skyward Sword, Mario Sunshine, Xenoblade Chronicles X