In Pve it lets you get into position to use your Maul, also in instances, you can get into position, sneak up behind their healer, or the guy in cover.. And with it Stealthing your companion at the same time, it just makes for some nice Burst in pve. Sneak in, Maul a weak one, usually 1 hitting it. Overload the group. The Companion typically then jumps at one with it's charge. pick one he didn't go after, Shock it as you run up to it, and if it was dazed, maul it again. quite fun little combos

The option to match your gear colour to your chest, is not going to be in a launch.. it was in during early beta, but was disabled near the end of Beta's. They are currently working on a similiar system, but it wont be in right at launch. You can hide your Helmet, but if your Robe has a Hood, it will be up. There was no option to lower a hood on a robe that i found.

It also depends what angle you approach things from.. if you walk straigh up to their face, they will see you a lot easier. you will also get something above your head, warning you they have detected you. they wont attack right away, but if you don't move away quickly they will fight you.