Inbox Pro is a productivity booster, and its signature feature is awesome in and of itself. It creates a professional, clean signature which really keeps your brand on point. The tracking function is super handy for making sure your emails get read, and analytics to keep you on your toes. Once the follow up sequences have variables, this product will really shine. Of course, there were a few hiccups along the way, and support has been excellent in navigating Google's "lovely" platform quirks.

I'm really looking forward to the Inbox Shield and other features on the roadmap.
In addition, I would really love to see further customization on the signature IE. Add your Tag line / USP, etc.