well, i can learn if Rengar can stop killing at .11 secs with only two kills XD. (Yes, it is possible to kill you with only two kills in .11 secs, with two kills).
When i play tanky supps, i can more easily deal with the preventing of a double kill, but chances are the first carry is dead immidiately. Coplaining is healthy for the game, it will help make Rengar a rewarding champion, not just a half-assed poorly balanced champ that Riot just crapped out one day. A rework, which will be the ultimate goal, is needed for Rengar, which may change things more to make him a more appealing champion overall. He rewards you too much for too little, which makes you feel underwhelmed or let down in the overall quality of the champ. Other champs that give me a similar feel when i use them are Fizz, Talon, Katarina, Taric, Yorick, Singed, and Shaco.
If say, Rendar took more mechanical skill to play, say like Zed or LeBlanc, then i would be perfectly fine with that since it can justify freebee power.
I like to try out and play as many champs as i can, and if i feel a champ is rewarding enough for the skill supposed skill cap (sometimes Riot claims a champ takes a lot of skill when they clearly don't, looking at you Katarina), then i love to play those champs more. This tend to happen with Skill shot based champs, not the point and click ones, which seem to be so "unfun" to play.
Rengar needs a rework, not only for his unjustified power, but also to make him a more fun to learn champ (right now, you ult, jump em, maybe, if you need to finish off a tank, use all abilities). Feels kind of like using Talon or Fizz, funny at times to one shot an enemy for doing so little (you can see videos of some funny newb ups that are rewarded as these champs), but laughs aside, we need to actually make his kit more balanced.