I ALWAYS wait for the sale for the newest Ass Creed title; that shit goes on sale within 1.5 months of its release (granted, it's only about $10 by that point, but then they have the $20 off the next sale that rolls around).
I will add myself that this game is worth every penny you buy it for regardless.
What I've seen/played so far has been really nice, and Rockstar definitely shows their work to be a labor of love, but it still feels like they had a blast creating the world, the setting, the people, the dialogue, the minigames, and so on.