For this gamer, animeeples are a must when playing Agricola. Most importantly they increase the accessability of the game. People may not be intrested in breeding three different colors of cubes, but everyone seems to want to move little sheep around the board. In addition, being able to identify the animals at a glance smoothes out gameplay, giving time for strategy.
Finally, the production quality of the particular animeeples is very high. I would recommend them to anyone serious about Agricola!
Well it obviously has no bearance on the game itself, but Agricola's substitute animeeples are pretty cute. They're pretty popular, too, so it just goes to show you that people love putting a little form to an abstract concept. Agricola's base pieces are little cubes.