His downside is a slow clear time and no hard cc until 6. That being said, he has great mobility, along with great damage, so he's a little similar to a lee sin jungle with worse clear and utility, but with ap. Since he is an auto based ap jungler, he's best with a ff for clear time, but he's not shabby with a elder lizard or golem, but all of them really don't fit with optimal build paths.
Also, it dawned on me yesterday that malzahar should totally have a legendary skin called Beekeeper Malzahar, with big bees for voidlings, two swarms of bees for q, bees errwhere for w, bees for e, and bees pouring out of his mouth for his r. I would pay top price for that skin.