Haku was so easy to pick up in CS. Just by watching videos I already knew his optimal combos coming into CS, and the transition was awesome. They pretty much just added to what he had. Only thing I had to get used to was cutting projectiles and such.
As for learning other chars I'll agree to the other poster that in CS characters aren't pick-up and play. In CT I learned almost everyone's combos and just mashed with 'em and it worked pretty well, but now the characters feel much more specialized and defined, so it's been harder for me to pick up extra characters. (which is fine, I'm still working on getting Mu up)
Good luck to you, good sir in learning new characters :D
You'll need it :3