Yeah, the gas port venting under the handguard is the one design decision I find myself unhappy w/ on the VZ58. Otherwise, I can't say I have any other major complaints. Aftermarket handguards that allow better ventilation than beaver barf help here, but don't fully solve the heat issue...
From a convenience standpoint, I would prefer an easier bolt disassembly, but everything else in the convenience realm is easily corrected w/ the aftermarket tactical bolt releases, ambi mag release, ambi safety, swapping the bolt handle to right side (I'm sure that this was required by the Soviets to mimic the AK platform mechanics), and that's about it.