Episode 2 felt like his first time doing the character. I suppose I get that it's meant to establish how different Aku's become in complacency while still knowing that Jack is out there.
Episode 5 was good. The delivery on "Malaise", the audible "I'm just fucking done" tone after he rekts Scotsman, etc.
The flashback in Episode 7 was tremendous, though. He had the intonation of the character down from the start, but here he had the ENERGY that Aku always had. It's convinced me that Aku sounding off in the first two appearances (and the two times he's been heard over the phone with Scaramouche) might be on purpose.
I'm exciting to hear Greg's delivery towards the climax of the season.