I've probably played vi in the jungle 50+ times. For a while I was absolutely hooked and I'd still probably be playing her if my team didn't suddenly need a top laner. I haven't played vi since the bug fixes, but i'll say that I like her more than shyv for a few reasons.
I tend to focus on my early game as much as possible with her since she has a great clear speed. This means wriggles and mobility boots. This provides you with faster clears, some sustain from life steal, better counter Jungling, a free ward to place at baron or one of their buffs, and better timed gangs/pressure for your lanes.
After that its pretty simple. First brutalizer or phage depending on comp. If absolutely no one else is going to buy aegis i'll get that. Next brutalizer or phage, then upgrade both of those. Usually game ends by then.
As reds, flat armor yellows, scaling Mr blues, and ms quints. 21/9/0 forgoing the crit based and dmg % talents for more cdr and dmg to minions. Skill order is w, e, q, q or e, and after that r > q > w > e. I max q because when you max e you can only get 1 q off during a spell combo. With a maxed q you can open, and close with it usually. --- There's far too much trash in the universe.
Her pre 6 ganks are average, but that is ok same with many top tier junglers.
Her post 6 ganks are amazing.
Her clear time is shockingly good even if you don't start machete [or build it into anything]
She duels well.
She snowballs and carries well.
She doesn't really get low or anything [at least not more than every other jungler]
She is not blue buff dependent ever. This is one of my favorite things. Some junglers even if I don't need it, it still helps a ton if we have a manaless mid that lets me have it. Vi it helps for cdr of course, but just the mana is not an issue ever. Not even early levels.
Honestly, the first 2 times I played vi I legitimately didn't realize she used mana [I guess I thought she was like garen or something haha,w asn't paying too much attention those games]
She also counterjungles well.
Prob the only thing about her is she can be kitable, but that is about it.