Yea he can jungle better than b4 with his rockets, but im sorry the game isnt about jungleing sure haveing one person or two jungleing can help u out but u have 5 persons on a team most ppl should not be jungleing. He is less usefull to his team. He wass able to completely shut down a lane solo b4, he cant do that anymore. Shutting down one lane is very usefull to the team, he dosent need to jungle because he is getting every minion kill in that lane racking up minion kills faster than anyone else. His 3 turrets now cant even defend a lane from minions, superminions will rip through his 3 no HP turrets.
Yes he can push a lane with keep on seeting up turrets and push the lane back with grenades and stuff, but he could have done that same thing b4 also, of course most ppl would push slower as to keep there turrets together so if 3 ppl came to jump him he wouldnt die. He pushed slower but his inability to get pushed back made him far more effective pusher, now u can just have 1 person go after hemi and kill him.
Part of hemi is his passive which is the only way u can heal a turret up. The old hemi was able to save turrets at almost no HP and heal them up to full, takes a long time btw, though his 6 turrets are able to defend the turret for long enought to do that. His turrets now will not be able to defend the turret for long enough to heal the turret back up.
Besides there are much better farming champs then hemi, such as warwick, for jungleing lifesteal is the most important stat because it allows u to kill without loseing any HP so u dont have to go back to town every so often, Hemi dosent have that, and is heavy mana dependant also, so thouse 2 issues would slow down his jungleing. Ontop of lizard buff not being of much use to hemi. Were as warwick, yi, udyr, teemo, shaco both buffs are useful.
Plus u say he is fine except his ult, where as ults are suppost to be ur most important skill, so right there u are saying he is not fine. The ult i listed above would be a very usefull one Plus u could still jungle with turrets and grenades if u really want 2.