A while back, I had the opportunity to talk to one of the engineers at Gore (owns Sitka; think Gore-tex) and review some of the science behind Sitka and camouflage, in general. Interestingly, animals don't really discern the different camo patterns and the ones on the market are more about making us, as people, feel better. Sitka gets the edge because of the digital/fractal pattern that truly breaks up outlines and makes us harder to see by animals. There are several high quality clothing lines out there now, but I agree with others: you get what you pay for.
Having said that, I love my Sitka. When hiking in some of the rough country out here, it really does feel more comfortable, especially when you start going up some of the steep slopes. You don'g get that stretch in the crotch or pulling (combined with said stretch) in the thighs that you do with other types of camo clothing. Their new whitetail line is great and I've started stocking up on that for my hunts in the forested country out there.