Unless that platform has changed completely in the last year or so then they are wrong. Appcelerator (and things like it) generally make "Hello World" super easy and even the first week or two will be awesome. Then the cracks will start to show. You will add a listener on a button and the app starts crashing with a cryptic error, you start having to litter your code with `if(isAndroid)`/`if(isIOS)`, or for some reason a view will be really show to render to lag between clicking and doing something. When you get down to it you'd be better off learning native or just accepting a mobile website instead. Normally (IMHO) the only apps worth using appcelerator for are simple websites and at that point you'd be better off just doing a mobile website.

I'm excited to play with React Native but I fear it will suffer from the same issues.