I guess my two concerns about solutions like this are always A) vendor lock-in B) whether it's too big of a project for any one company and requires a community of contributors to realize the vision.
In the short term it doesn't really matter because clearly being able to build an app is a huge step up from not being able to build an app regardless (which is why companies like Bubble.is are doing so well), but in the long term it seems like there are 10 - 15 companies working on this so eventually there will be more options and those factors will be key differentiators.