Very great customer support, which is helpful and super fast. Hubsell is probably the best product on the market to send out highly targeted outbound campaigns.
It helps automate mails. I also like the customization features that help me tailer a campaign completely to each vertical.
Nice overview of the actual stats including sentiment analysis of the replies. API to my favorite CRM - pipedreive Others as well, like salesforce etc.
Sometimes it gives you prospects which are not connected to your field and it wasting your time to check them.
I think the email sending aspect isn't overly intuitive, it doesn't highlight when there is an error, therefore you expect something to go and it doesn't but you don't notice for over a day.
Maybe some tricky in the first use but you learn it fast when you use it.