great graphics remain a subjective factor for social game developers. To help further refine the argument that it is valuable, I consider three areas related to those discussed above: retaining initial installs of new players, better monetization of virtual goods, and extending game-play durations. These areas all play a large part in a games’ success or failure in an increasingly competitive market.

Useful guest post at Inside Social Games discusses three areas to which quality art can contribute in social games. Reminds me of the 'sparkles per second' principle that e.g. the Playdom folks mentioned at GDC Europe: animations and 'sparkle' matter, both for purely aesthetic purposes but also for directing the players' attention.