I like that it is easy to set up, has lots of great features (including tagging), integrates with MailChimp so we can pull in data from our other platforms as well! The only thing about this program is how many steps there are between each action taken by your customers once they have replied/engaged you via email or phone call.
It would be helpful if actions could take place immediately after an interaction was made - instead having them go through another step first before being able to engage someone else within my team when replying back. This helps us ensure everyone responds quickly which then results in more leads for future projects / opportunities etc...