The best thing about this product was it's simplicity which helped me manage my marketing campaigns very efficiently! I can see at any given point in time what are all of our active users who haven't yet made their first purchase from us, or those who have bought but need additional information before we make them another offer - This allows you to be more targeted when sending emails/ads etc. We've also found they're quite good value too, particularly if you don't already use other services like Mailchimp / Hubspot (both £99 per month). There really isn't anything majorly negative here so far. Nothing comes up often enough that makes this worth not switching over completely. If your email service provider doesn't provide great integrations into HubSpot then maybe consider looking elsewhere? They do however integrate well within Salesforce via Zapier allowing easy data sharing between both platforms.