Grassophers are the posh team of Zurich and as such, don't have that much support. Zurich are the working-class team and they have much better support, in quantity and quality. This year, because they have to play at the Hardturm, whilst the Letzigrund is being re-done for Euro2008, they have much reduced their "tifo" activity but last season was quite something from them, it very much impressed across continental Europe, with superb displays in the stands.
Football wise, it's not Premiership but it's not Conference either, if you like the game, it's worth going, particularly considering the price you'll have to pay (yep, Switzerland is cheap for football!).
Anyhow,k 22nd of April will be the big one, with Basel-FCZ, if it is just half as spectacular as last year's game, it will be a treat! http://www.efzezet.ch/pics/movies/fcz0506.wmv