Data management is somewhat clunky, especially around editing and reassigning contacts.
No visibility of related contacts or duplicates across campaigns. E.g. If you have a contact you're in touch with through one campaign in one company, it would be good to know if it has been reached out to on another campaign.
Definitely dislike how long it takes to get uspport. There are some things you cannot change yourself, such as attachment library size, of which you need more than 20MB if you're an agency with many clients. We have written and called several times over the last month to have this increased and still no response.