Dude, jungle blitz is dank as fuck. Your first clear is shit tier, but you have godly ganks after your first b. Overdrive gives you huge chase power, power fist is massive early game cc, and rocket grab can force flashes, or punish early flashes.
WE'RE BACK BOYZZZ. [Tons of pics inside]
Sure, but his damage is stupid low early. If you're looking for someone reliable with good cc and early damage just pick jarvan or xin. They both have slows and knockups, and they are actual damage threats. The only way I see a blitz jungle working is if you had like, fiora top lane and azir mid or something. You'd need high damage carries.
His ult is 100 damage every 2.5 seconds with the option to silence enemies for .5 seconds and deal 250 aoe damage at level 1. With a basic rune and mastery setup, blitz should have around 70 ad at level 1, which means an auto e auto combo would deal 280 damage before mitigation at level 1 with no items. Assuming 30% mitigation from armor, you're dealing 200 damage and knocking up somebody for 25 mana at level 1. That's a third of most champion's starting health.
His ult is very unreliable on the random damage. The silence is there, but is pretty negligible if you're playing him jungle. The damage on his ult is also pretty low compared to others.
You seem pretty set on comparing him to nautilus. With that same rune/mastery setup, he would have around the same ad, maybe 2 less. Nautilus' autos snare for .5 seconds on auto. Now at level one, you have your shield. If for some unrealistic reason a blitzcrank and nautilus get into a level 1 jungle fight, nautilus would do 210 from the auto, w auto, auto. Then you factor in the DoT from his W, which is 40 per hit. That leaves his damage at 290. Take away about 25 from that since the DoT doesn't overlap. So 265. Same mitigation, 30%, so 185 damage. Along with a 100 hp shield.
Now, that is pretty unlikely that will happen. But I would argue that nautilus has just as strong of picks as blitz does, with the exception of being able to pull people through walls. He has more reliable cc, and more of it, with a slow on his e, stun on his q, aoe knockup on his ult, and a snare each auto. I would say he has MUCH better teamfighting than blitz does, being able to lock down a target without needing line of fire like blitz would for a hook.
Are people seriously trying to argue Blitzcrank isn't an amazing champion? Did you even see CLGs recent games?
If Aphromoo can win a pro level game for his team using him, chances are the bronze/silver/gold/whatever players in this thread aren't using him to his potential.