Is Udyr OP?

Nope, the only reason he may seem OP is because of Sated Devourer, which makes alot of junglers broken.

Besides sated/devourer making him op (like everyone else) the only other change I would suggest is making his move speed boost from bear stance reduced or eliminated when running away. Asides from being very difficult to punish his mistakes since he stuns you, then runs away absurdly fast, it does not capture the spirit of the bear. Bears, while they can sometimes run away from fights, are generally more well known for being vicious and chasing you down like a truck.

TL;DR: Bear stance move speed boost should not apply at full strength (or at all) when running AWAY from an enemy.

His relative power drops like a rock at level 6. Just don't let him free farm and he's a kitten come late game.

garen deals tons of damage with no items too, guess whos getting kited easily too.

With Sated, he is extremely broken. It really powers up his Tiger and Phoenix stances.