WooCommerce is free which is a price you can’t beat. There are already 9 extensions along with 6 compatible themes with more of both on the way. I think the WooThemes crew is going about this the right way by providing a stellar e-commerce product at a free price while offering pay for add-ons to increase the functionality.

Free is only a gimmick if you cannot realistically run a store without having to buy the add-ons.

I haven't had a chance to look at Woocommerce, I might well use it, but users should always look past the marketing bullshit and investigate the real, long-term costs before investing time into any plugin. Woo have an established reputation, managing to make it into the final 32 Theme companies by popular vote in WPCandy's Theme Madness competition earlier this year, but they tend to be expensive and their prices will be rising in January.

On a related note, I would love to see a review of how easy or complicated it is to keep all these add-ons updated. Splitting off functionality into add-ons is a commercial/marketing decision - one also taken by Shopp and WP E-commerce among others - but I wonder if that makes automatic updating trickier. Having to update all those add-ons on a bunch of different sites could chew up a lot of your time.