With unrest just around the corner this is a usefull peice of equipment. Before heading in there, and if you have the time take a quick look around to see if Jetsam is nearby for a maybe lucky escape route in unrest.
If I got one of these off of jetsam, i would probably save it (believe its insta invis).
I do agree with the escape route thing. Before anyone starts flaming me, let me explain. Combined with run speed, insta invis is a lifesaver. Lets you run to zone without sight agro (not counting help agro). This allows you to get a few steps away from mobs before they attack you. This lets you escape some casters, not get stunned, and generaly make it to the zone line. The mob that you are attacking will still hit you, but just him and just for a short time.