Some guys will tell you that you need the latest and greatest camouflage, carbon lined to eliminate scent, with highly detailed patterns.
Really, all you need is something to break up your outline. The old-school tree-bark camo probably works just as good as complex patterns, or better. Heck, some guys hunt with just plaid and do fine!
Bottom line for me: make sure it's quiet, comfortable, durable, and warm. As long as the pattern isn't completely out to lunch (i.e. snow camo in autumn) I think you'll be fine.