It's not the greatest-playing platformer on the Genesis (it's okay, not bad, just average) but it's one of those amazing-looking late-era Genesis games that gets largely overlooked because of the license and also because the next-gen systems like the Saturn and Playstation (and, yes, 3DO and Jaguar) made 2D games old news.
This game is comparable to the Genesis version of Disney's Aladdin in that they got actual artists from PAWS, INC. who work on the comic strip (no big secret that Jim Davis didn't draw it much after the first couple of years) to work on the sprites and backgrounds. They might have also got some of the animators from the then recently-concluded Garfield & Friends TV series as well, though I'm not 100% sure about that one.
Oh, totally. It was a weird time for newspaper comics. They had a degree of authority over pop culture that is historically unparalleled. It's kind of sad that Dilbert is the last of the "big" comic strips.
Garfield really has a weird style that they've kind of stuck to for decades. It's a bit more cartoony and slapstick heavy than, say Haggar the Horrible or Blondie which have been going forever under different artists. I always wonder about those anonymous artists at PAWS, INC. Also totally agree with the B. Kliban observation.
The ending is a "Nice Touch", an in-joke for fans of the TV specials (in which Lorenzo Music Garfield looks to the camera and think-speaks "Nice Touch" at some point in each one).