I am a fan of custom solutions most of the time (its easier to build small custom solutions then to find a ready made solution online, at least what I think), and I used to code small ecommerce sites myself, carts, checkouts, payment gateways integrations, and after some experience I started thinking about building something which I could re-use with little or not changes on every new ecommerce site I build.
But during that time woocommerce was emerging, and off course I kept looking for ecommerce solutions for wordpress but found no reliable one :(, but when I stumbled upon woocommerce back in its early stages, first thing I did was dived into its code and learn how they did it, and then I used those coding techniques on my ecommerce site, but I was not ready to adapt it, but when they released 2.0, I couldn't hesitate to embrace it. And since then I still write custom ecommerce code but for woocommerce ;) (for every project special needs), and I must say I liked it because this is how I would have built an ecommerce solution (if I could :D), and it meets my coding style and flexible enought (though still need to go a long way) for most of my customizations needs.
So I am openly saying: I am loving it ;).
Thanks guys for such an awesome plugin.