I must admit, sneak is a bit insane at higher levels. I personally hate the perk system. If you are level 30, and want a level 30 perk, you still have to obtain the level 25 perk before it. For example, I did not want the sneak perk where stepping on a pressure plate no longer triggers it. I love trying to avoid stuff like that, but I was forced to take it if I wanted to get higher sneak perks. (Fortunately I'm playing on PC so I can remove it)
Also, the no longer need to be crouched perk, love hate there. There should've been a range for that, if I'm two feet behind someone, I should have to get back into a crouch, but again, love hate. It is fun sometimes to completely ninja rush someone but it makes things a bit too easy at times.