I think we can all agree that Garfield is one of the least funny comics ever to receive mass circulation. Garfield's sarcasm masks an entirely toothless, bland, inoffensive sense of humor. I guess it isn't horrible, but it's aggressively mediocre. Aside from that 'Death of Garfield' storyline(which is more a case of misinterpretation than anything else), there hasn't been anything in the strip to interest me since I turned 13.
That said, everyone needs to head over to Garfield Minus Garfield right now, where some glorious bastard had the bright idea to remove Garfield from the Garfield comic strips. The result is a hilarious collection of non-sequiturs and maudlin self reflection as John putters around his house, talking to himself and occasionally going crazy.