The last & only push notifications deal I bought was Zopush (which turned out to be a scam) and ever since I was on the lookout for a push notification service LTD that I could trust to stay in business. Gravitec is it. I'm so glad that I jumped the ship while the deal was on.
I have not used it on any of my websites yet, but I logged in and looked around to explore the UI and the features and I am very much pleased with what I see. If you are serious about increasing your consumer lifetime value and return visit rate, you can not miss this one.