He can sustain jungle, doesn't mean he can jungle fast or gank good. He got sustain which is good, but his damage output isn't that great. I mean the few buffs made him pretty strong, but other junglers outclass him. Plus his ultimate is a channeling spell, which therefore can be easily CC'ed out of it.
I usually end up not lantern and instead scepter + bloodrazor for a bit till I upgrade scepter to either bloodthirster or jsut get executioner calling but his jungle is pretty crazy and he doesnt turrets fast but he cant push a lane as fast as shyvana and shyvana has no mana so more sustain.
Still Tier 1-2 just not as godly as shyvana.
Late game his Q does over 20% on Champs adn with good CD reduction it is spamable (like greenbuff)