Great Car and Driver May 2017 issue review. Those guys write the best reviews.
I get the paper magazine, and it looks like the caranddriver.com website does NOT have it yet. Later for sure.
Libraries have it now.
Looks like most of the same criticisms of the related Niro apply to the Elantra-based Ioniq Hybrid. I'd get an Ioniq in full-electric (no gasoline engine on board) form, but not the hybrid form. (My other non-Cmax car is a Ford Focus Electric.) The same driveline clunkiness the Niro has haunts the Ioniq. Just not good enough for me. Our CMax is so smooth it spoils us.
Car and Driver said they got 45 MPG with the Ioniq with performance tires similar to our CMax's tires, which is exactly the MPG I get long-term in mixed driving in my CMax.
Besides the clunky Ioniq/Niro drivetrain, its a decent vehicle, priced kind of low.