Hey Gerard,
At my last company, the plugin for Outlook for was a hit - this time around not so much. Adoption of this feature will depend on training and advocacy within the org. The key benefits are the pre-made email templates and the open and click reporting. The reporting is in MSI in Salesforce so sales should already be in the habit of checking the module daily. If they are not, then it will be a difficult roll out.
In my successful case - sales and marketing met every week with frequent training sessions. I am now at a global company where it is challenging to align the multiple offices, time zones, and varying sales teams.
I do have a few users who like the tool and we are trying to generate wins that will spread. I would say: if you have the resources and bandwidth to plan and support the roll out that would be ideal.