I main jungle, and I enjoy playing non "mainstream" junglers. I like warwick because he is just trolly as f*** and I like fiddle because you go bot at lvl 6, ult over... "DOUBLE KILL!"
Anyway, this is my 1st ever guide, I have no idea how to use this website, so please don't be harsh and help me out ;)Should probably have more matches but its christmas/newyear!

Pros
Decent clear
Great sustain
Good ganks at level 6
Can trade with most junglers
Strong counter jungling
Badass

Cons
Not very good ganks until 6, but with red buff and E passive can chase top/bot very well.
Not a very powerful 1v2 ability, but can do it if fed
Needs blue if you just wanna clear the jungle instantly!

Generally, try to save your team mates (especially if they're not with you!) because most people think of Warwick jungle as a joke! But let me tell you, your a joke. Helping others out as warwick with your ult or giving them an AS buff to take turrets they'll appreciate it.
[*] Captain enchantment
This is very useful people since you are generally leading the pack

Ok, ok trolling with warwick in ranked is what people instantly assume when they see you lock in warwick jungle, they generally scream "NOOB LOL WANNA LOSE US THIS GAME? OK GG NO RE I TROLL NOW!". Then, if you're good, you just carry win the game and GG, because warwick is very good with this build to solo baron, you can do it quite early but i recommend doing it after you have spirit visage. So ye, picking warwick in ranked is ok, but just try to ignore the flamers.