We are in the process of developing a heavily customized Magento store which needs to support muti website, and multi stores, the mobile app will also need to easily switch from one store to another. What is the best option for the API selection? XMLConnect seems pretty efficient, but it seems only attached to one store and lacking documentation; REST API is in complete; SOAP API is too heavy...
Why Magento doesn't provide a complete set of REST API as the SOAP API?
Magento has created an SDK for iOS and Android development:
http://magento.com/blog/magento-news/introducing-enterprise-edition-1142
http://magento.com/blog/technical/enterprise-edition-11421-sdk-android-and-new-security-patch
If you would rather not purchase an Enterprise license or sign a partner agreement there is an SDK available for community from Agilemonkeys:
Magento has an incomplete REST API for doing full-blown sites. However, the Magento community has stepped up in a big way. Vinai Kopp put together a writeup that details what he had to build to provide the gateway to Single Page Application (in particular, with Angular) with stopgap REST support:
http://www.slideshare.net/meetmagentoes/one-page-shops-with-magento-angular-js-vinai
