I haven't tried new Malzahar but at first glance I'm iffy on the changes.
I actually do like his new passive, I liked to build Malzahar kind of tanky anyway so this fits my playstyle. I also like how the voidlings are now an ability, his old W was a filler, the new ult seems better to. Overall all the ability changes are good. What I really don't like is how they completely gutted the damage on his E to the point where it probably isn't worth maxing. I'm concerned about his burst taking a hit. I also don't like this jungle Malzahar trend, I never had any desire to play him in the jungle. What I liked about Malzahar is how you could build him like an AP bruiser and still deal really good damage. Now it seems like you can't do that.