This is pretty much as good as you can get within the cyberpunk genre, and it leads the vanguard of philosophical anime. This is not an action flick, even though the few combat scenes are visually stunning and well directed.
GitS took my anime virginity back in '99 or so, but even though it tickled my curiosity, it turns out it wasn't the one that got me hooked on the anime artform per se. See, this movie isn't what you would call typical for anime as far as tropes, memes and dramaturgy go. It owes a lot to western stuff in that regard, mainly Bladerunner of course.
Compared to Bladerunner though, GitS is superior in basically every aspect. It's deeper, more atmospheric, better looking etc etc. The only thing it lacks is Vangelis. Other than that, the only thing that stops me from giving GitS a solid 10 is that it's rather short. I usually consider this a plus, but a story this complex and deep needs time to bloom. This movie feels more like an introduction. Hopefully Stand alone complex et al will keep up the awesomeness, cuz that's where I'm heading now.