I have tested a few ERP/CRM solutions already. Some to mention are xTuple, Dollibar, openERP, and few others. I like ERPNext much more than the rest! One of the main advantages is the easiness of use of the accounting module and it's integration to warehouses and buying/selling operations.
However, there is still room for improvement in the accounting module. Mainly the inclusion of P&L and Cash flow. I think there can be some simplification to the advance payment, and phased (milestone) payments methods of purchasing.
One of the things that can be improved as well is a "business intelligence dashboard". This perhaps requires some brain storming and collaboration from the users to decide what is can tell the business operational excellence in a single glance.
All in all, I am loving ERPNext everyday, and perhaps soon enough I will be recommending it to my sister companies too.
Regards,
Ahmed