Volibear isn't a top-tier pick competitively, but he's still a really straight-forward and reliable champion. If you're interested in playing him just go for it.
He lost a lot of strength as a jungler since the jungle rework. And he might be even weaker overall after the tank item changes this mid season patch (lots of tank items give less hp :/).
He's still playable for sure, but he's probably a low tier jungler now.
Turbo Chemtank and Stalker's Blade - Cinderhulk are really good on him, particularly as a jungler. I recommend trying that opening if you haven't already.
He's still playable for sure, but he's probably a low tier jungler now.
EDIT: *A very strong jungler.