The most useful part is that it provides me with all my contact details, so I can follow up directly from here without having another system open! It's not very intuitive at first but once one gets used they realize how great this tool really works - even if we're just looking through our contacts list or emails/emails sent out by us as an agency (which are usually automated).
We've been able use rocks&gold since April 2016 when implementing into hubspot CRM platform which was previously using other software like Salesforce etc..