Finished Grisaia No Kajitsu.  Can't really say much that hasn't been already said.  The common route is really funny with awesome character interactions and good comedy.  It might drag a little sometimes, but there are enough funny scenes spread around where it's not really that big of a problem.  Probably the best common route I've played to date.  I liked all the characters.  Sachi in particular ended up going pretty high on the list because I loved her comedy.     
As far as routes are concerned, this one is a bit tough.  Makina and Amane had the best routes IMO.  I agree with Harle that it's kind of tough for me to say whether Makina or Amane is better.  I enjoyed them equally as routes really.  Makina's bad end was really nice, and Amane's flashback was one of the high points in the game.  If I had to pick, I'd probably say Makina by just a tiny hair.  Next is Sachi.  As I said, I really enjoyed her as a character, so this route was entertaining to me overall.  It might drag a little in the middle for some people, but it wasn't too much of a problem for me.  Michiru's route was crazy as fuck, but enjoyable overall.  Yumiko is last, which is kinda disappointing since I liked her character.  But the pacing just wasn't right in the route and the ending(s) weren't that good.  But like I said, this VN does have some nice characters, great interactions (which doesn't stop in the common route btw), and great comedy (along with your drama ofc).     
As far as the music is concerned, some tracks were good.  But yeah, definitely not enough tracks for a 50-60+ hour VN.  I heard they really pumped up production values in Rakuen, so we should see some awesome stuff in there.  Not totally sure about the rating yet, but it's in the 8 to 8.5 range for me.  Patiently waiting for the sequels.