I like that we have an easy way of making sales calls from our website without having any third party involved in between us as Salesforce does not allow it out-of box which means you need another vendor or tool if your looking at doing this with SFDC alone - but partnerstack makes all these problems go away by providing everything needed within one solution (Sales Cloud + CPQ).
The reporting options are great too! We've been able solve some issues around customer success using CSM's and other tools they provide through thematic flows when creating new customers etc.,.