@Riot are you planning to do anything else to Viktor?
I get the idea of reducing his upfront burst, but the changes to death ray just make it feel really awkward to use. Viktor's E is his most unique and interesting ability, and it feels awful to have your main ability be mostly reliant on allied CC to be useful for anything other than clearing waves.
If you moved the delay to some midpoint between the current and old values and reverted the missile speed change, he'd feel a lot less clunky to play while still keeping the core changes.
His new ult is actually really fun to use, but it's overshadowed by his E being a clunky mess. It's just too many cc reliant delays on a champion who can't reliably cc targets.