These guys seem to be copying the Parse business model. Which as we all know worked out very nicely for the founders and investors. But very badly for anyone that adopted the Parse framework.
I hesitatingly and begrudgingly used parse while it was still hosted by Facebook. At the time my biggest and only problem with it was the vendor lock-in. Now that it's open source, that problem no longer exists, and all the great tooling is still around.
I'm happily using it on new projects. I suggest taking a look and trying it yourself.