I used it and watched high school students use it for a couple of hours/week over a period of 8 weeks (varying degrees of technical expertise, in an entrepreneurship mentorship program with an end goal of the students building their own apps) and found that while the easy access to phone functions is pretty cool, it's still very limited and clearly aimed at non-programmers (think scratch).

likes:

- lots of powerful features that make necessary mobile app features (e.g. "pull up your contacts list!") super easy

- "puzzle piece" logic building inside app inventor is really easy to understand (ish), and pretty well done

- the process* is easy for non-programmers to do / understand / see in action

dislikes:

- how difficult it is to go beyond app inventor's available functions, if you know exactly what you want to do, or how you would do it if you could just pull up code (e.g. it's really hard / awkward right now to have multiple "screens" in an app)

- the android "look" in general, and the strict limitations of app inventor wrt visual styling

- the emulator is, unfortunately, _not_ easily accessible for non-programmers

- everything runs inside a java vm, and generally feels a little cumbersome

- the process* is slow and full of 30-second chunks of lost time

* process: make changes to the program -> "package" the app -> take a photo of the generated QR code -> download and install the app -> test your changes on the phone