I shared about Sendpulse last year last year when I made the decision to move all my email marketing over to them from aWeber and a while after moving my list to them I started playing around with their PUSH notifications. The results have been awesome, I am loving PUSH notifications.
Signing up with Sendpulse is free up 2500 email subscribers and up to 25 000 emails per month, however PUSH notifications is completely free. You can have unlimited PUSH subscribers and send out as many pushes as you like at no cost.
I have found the subscribe rate for PUSH to be much higher than email and the click through rate is also much better.
Added to that sending out a push is so fast and easy - nothing compared to the time taken to design and write an email!
If you have any questions let me know in the comments!