^I think it's more a case of Powell's style being more cartoony (for lack of a better word) than the interior art.
I'm actually becoming more and more fond of the cartoony side of comic book art (a few months of reading Popeye and Scrooge McDuck comics will do that I s'pose) and wouldn't mind a Godzilla comic done in that style - but having cartoony covers and more realistic, mainstream art on the inside is kind of a weird break.
That being said, I'd love a cover by Stan Sakai! :
Oh, and I just figured out why I felt that issue 4 cover by Powell had less effort put into it than his other: the others were strait-up paintings and this one appears to be a drawing (with some paintiung elements).