Since there seems to be so many topics started by people who would like advice on an assassin/stealth build and play, http://www.youtube.com/watch?v=2qbjrljELjo&feature=youtu.be.
This isn't my best playing that's in the video (see other videos) but I think it conveys to those looking for new ideas on what they can do with the path of shadow.
Not trying to suggest my way is "correct" but I think it serves better than the more basic tutorials found on youtube.

The last perk in stealth is pretty pointless. I personally haven't found a use for shadow warrior.

You can slit someone's throat instantly if your standing right next to them. You have to be the right distance though otherwise it wont work.