I like that it's easy to use,it works well with most CMSs (WordPress).
And all of my contacts are in one place so there aren't duplicate emails getting sent out from multiple people who have access or control over different parts of our account. It would be nice if they could add more filters for contact data such as location, age range etc. but overall nothing really! We've been able to reduce email bounces by 90% since using this tool we can see what content users respond best too when sending bulk emails through our system which helps us create better marketing campaigns and increase engagement rates.