I'll give a detailed (and serious) opinion on it now since i'm the only person who's actually tested it out.
Ganks: Her ganks are mediocre in a lane that provides no cc. In this case though I had Rengar, who's E and ult E made securing kills relatively easy.
Early Game: The damage she brings in a gank is actually not that bad with the double passive proc. From what i've seen though, she's really prone to counter jungling due to most of the top tier junglers (Lee Sin, Elise, Vi etc.) being able to 1v1 her and come out with a good amount of health.
Objective Secure: Junglers like Lee and Elise have an execute on their Q which allows them to pretty much just add more damage to their smite, whereas Quinn has to rely on her E to burst an objective, and even then it leaves the opponent room to out play and smite steal from you. It's also worth noting that she has no way to dodge AoE cc and has nothing to lock down or reposition enemy junglers in a contest.
Clear: This is honestly what really hurts her. Her clear time is atrocious... like, we're talking Libra loading time bad. Although, if you're up for banking on your passive to proc on the big wolf or wraith then be my guest. You can't face tank the buffs or you'll end up pulling a Brokenshard. Luckily, you can easily kite them around with correct positioning.
Scaling: Blue Build Quinn did more damage than I gave her credit for, but that doesn't even matter due to the fact that you're forced to go in to get your Iceborn procs. I started that game 7/1 and I ended up dying multiple times attempting to assassinate the enemy carry in a team fight. She's great at picks, but that's about all she's good for from what i've seen.
There you go! That's my opinion on the whole thing; feel free to tell me if I missed anything or if you don't agree with something because i'd actually enjoy discussing it. Blue Build Jungle Quinn was hella fun to play and we all had a good time in that game c: