Hi Shirleen,
Our sales team really likes the plug in. It allows them to have normal back and forth trackable conversations with prospects instead of one-off's through SFDC. There are some great features of the add-in and some limitations (that you can still perform in MSI in SFDC).
To me, the biggest part of the success and adoption of this tool is the training. So if you do implement it, I'd recommend having those plans in order from the get-go.
Hope this helps!
Kim