* Lack of documentation. Every time, when i want to do something more than "todo app", i have to read the source code. Well, it's OK and a programmer has to read the source code to understand whats going on under the hood, but a little bit more good documentation can be really helpful.
* Examples are so simple. In a read world app it's more complicated. I have model ( persons ) and this model has collections ( contact datas, invoices etc. ) to find a way to handle all the mess i spend a weekend and read useless tutorials. In the end i gave up, read source code and my builded app on events. A better example could save my time and if there was a "best practices" guide, i could be sure that i'm on the right track.