Email integration, custom properties, saved views, tasks, flexible pipeline and deal stages, and Zapier integration. (oh and its free)
Some real limitations with the API, needs more team and record level security options.
I've been using HubSpot CRM since it was in Beta and it's really matured into a powerful CRM. I do pay for the Sales Pro tools which unlock a lot of power. There are some limitations however that make it a bad fit, you can read more about those in this review - https://www.techsmartboss.com/blog/top-things-you-should-know-about-the-limitations-of-hubspot-crm-with-workarounds/