It's hard not to say "NONE" but yes there are a couple things that bug me already.
#0 - Zero because I knew this going into the purchase. Wow is it bumpy! It's fun most of the time but sometimes a good bump will lift me right out of my seat. Considering a 5 point harness (for a street car! HAHAHA. No seriously).
#1 When I lower my right arm down to prepare for a shift, I often hit the traction control or driving mode switch. I don't realize it until some time later. I've since set my car to change interior lighting color to match the driving mode. This helps to alert me that I've inadvertently bumped the driving mode, but not the traction control. It's annoying, is there an aftermarket switch cover?
#2 One considerable reason I switched from a Z06 to a ZL1 was so my 2 year old daughter could come along but her car seat BARELY fits and when it does it blocks part of my rear view mirror.
#3 Why no front bumper camera like the Z06 ? I'm reintroducing the habit to back into parking spaces but its not always convenient.
#4 The top of the line camaro should have been given fancy fender vents like the Z06 or the GT350. IMO that area on the ZL1 is kind of bare.
#5 Rear seat doesn't fold down on the ZL1 1LE :( Not true
Having said that -- all things considered
I enjoy this car more than my 2017 Z06 w/ Z07