Well, having in mind that sneak has been reworked since the wipe, I played a sneaker character for some time. It was 5/10/4/1/9/6/6, small frame, good natured, it can have 220% sneak and 200% SG at the level 21. If it's good - I would say it's quite optional - you can stay 3 hexes behind your enemy without being visible, 5-6 hexes when on side, but bear in mind that you will always be visible when standing in front of a target (I tested it having 150% on the skill). It is an advantage for a town bluesuit hunter

, not quite useful in more organised PvP though.