Good for a small applications, but not so good when the complexity of the application is high.
What is most valuable?
* One of the main advantages I look for with titanium is its cross platform development (iPhone, iPad, iPod, Android, Windows, Linux and OS X).
* Single code base for mutli platforms so that managing an application becomes easier.
* It is open source.
* Offers flexibility as it using JavaScript.
What needs improvement?
* Documentation is shoddy and outdated.
* API calls have not been brushed up.
* Company support isn't all that great.
* Outdated videos have not been removed from the tutorial page, which are certainly, to some level, misleading to learning developers.
* Recently apple rejected an application of my co-worker for making private api calls (because apple does not allow you to make private api calls).
* Appcelerator provides StoreKit, a module to enable an In-App Purchase to Apple’s App Store, but it is very buggy and poorly documented. Therefore, it is not fit for production and may cause you to miss out on an important feature from your commercial app.
* Titanium Studio, provided for development on titanium, happens to ignore changes while building and at times it stops printing console messages, so that every time you have to test your code, you have to clean your project. An additional task to be done every time for testing a code, is not good at all.
* Animations are lagging, particularly on android devices.
* Poor performance of graphic intense games.
*Disclosure: I am a real user, and this review is based on my own experience and opinions.