Rengar's ultimate feels a little too noticeable.
In all honesty Rengar's ultimate is basically just creating a bush in front of your enemy, because if they see the exclamation mark above their head they basically know that you're: A) Jumping on the enemy carry. B) Jumping within the next 5 seconds. C) That you're within what is it, 1500 units? (Might be over exaggerated I have no idea)
I feel like Rengar loses his all of his kill potential and effectiveness unless the enemy ADC or mid laner was dumb enough to be walking alone past 30 minutes against a Rengar, or not sticking near his support and tanks for peel in a teamfight. Sure he can kill someone on the rare occasion one of the enemy carries isn't standing next to his tank jungler or support, but 9/10 times he completely useless.