Yeah. I recommend not watching Days until after II, though. And CoM is pretty brilliant, so you have that to look forward to.

But yeah, there really is no point going into 3D without the others. There's Days and BbS that give you the full meaning if you know all the other games, but the stuff in 3D is pretty much incomprehensible without all the other games (it's pretty crazy even if you do) because it's meant to tie them all up together before KH III.