The ease of use, quick setup/implementation time compared to other solutions we have used before with similar needs (Zoho CRM).
Support from AsService has been excellent as well! Nothing so far that I can think would be improved upon for our current requirements - but if there was something it'd probably just improve customer support even more!! We're using this primarily because ZOHO does not provide an option like ours within their product line yet; however they are working towards adding one soon which will make us choose between them or another solution all over again. Have had great success thus-far solving problems related specifically around managing contacts via email addresses rather than contact info stored elsewhere such as LinkedIn profiles etc., also being able to create custom fields without having access rights priorly required by some platforms out ther ein order get these features.