Very robust CRM tracking
Integrates well across the email platforms we use.
API also integrates well with other inbound marketing software we currently use.
Many useful apps in their AppExchange.
Room for Improvement:
Takes a long time to get fully up and running on Salesforce.
We've noticed a few bugs that haven't been worked out (although Salesforce support team is great)
It's quite expensive on a per user basis.
Overall, I would recommend Salesforce, as it's an industry leader and integrates well across multiple platforms. However, it is expensive, and took a long time for my team to fully adopt Salesforce and to use it without having any issues.