This just seems like the crappiest idea ever. Maybe if it was animated like Shrek (I guess "computer animated", but isn't everything animated by computers nowadays?) it would actually be cool. But live-action? It's going to look like shit, especially if there's a lot of emphasis on Garfield and Odie. They might as well just make Bill Murray wear a plastic Garfield mask with eyes cut out of it and a rubber band around the back. And he'll wear a suit and tie. And the vet scene will be priceless.
On second thought, the crappier they make it, the better it will be.