I've used this for almost a year now, and can give a pretty candid review.

First of all, the value for this deal is VERY good. If you're needing Push Notifications for your site, then you aren't going to find higher quality software at a better price.

The welcome notifications are easy to setup on Wordpress (what I use), and sending a notification is easy - especially because it imports the SEO metadata & Wordpress Featured Image automatically for you.

The response is solid. Even after a year, my clickthrough rates continue to be 1%-3%.

The Weekly Digest seems to be hit-or-miss. I really like how it looks and that it can be automated. I felt a little misled by this feature, however, because I expected it to send ALL notifications that were missed by a subscriber. This isn't the case. It only sends the weekly digest if there were enough notifications through the week (I think the minimum threshold is 6).

Eventually, I decided I wanted to focus entirely on email subscribers so I uninstalled the Gravitec exit popup and replaced it with a Wordpress exit pop optin that integrates with SendFox (an AppSumo product I really like, btw). Even with the uninstall months ago, I still send Gravitec push notifications to the subscribers on that list.