I've been building a couple of simple apps on it the last few months, and it has been a pleasure.
I should be clear here -- I've been using Titanium, not Alloy.
I'm still new to the hybrid app world and have only used ionic. I want to eventually try one of these "native" frameworks though.
So, lesson for me was use titanium classic and NOT Alloy.
Also, I would advise building your own small framework with views (things like title bars etc). Just makes it so much easier to make it look and work exactly how you want on iOS and Android.
Once I took a step back to Titanium it all felt a lot more sane. Yes it is a little more verbose, but at least I can follow the data flow in code.
Appcelerator is going through some changes as of this week[1] which I hope will improve the documentation and ecosystem around the product.
[1] - http://techcrunch.com/2015/03/04/appcelerator-slashes-staff/