I started looking for a different traffic source when Facebook got "stormy". The test results left me satisfied. If you're just starting out with push notifications or are looking for a new place with them - this is a good venue. A fairly large selection of formats, that occasionally gets updated. The latest updated introduced calendar push notifications. They let send pushes to iOS devices right from the calendar app. A pretty cool update, worth a try.
This review reflects the subjective opinion of the user, and not the official position of the editors.