Is Appcelerator Titanium mature enough for professional app development for Android and iPhone?

It is mature for the development and you can ...

I have been in Appcelerator developer since 2010.  I can attest that while there are still problems with the Appcelerator platform the ability to build quality and solid apps is both proven by myself and other developers. Personally I have developed an application for national Bank for both iPad, iPhone and android that is still currently in use today with no issues.

Yes. Since 1.8+ version it's very mature to professional applications. Today, version is 2.1.3. And it's very nice. You can see some applications made with Titanium here: http://builtwithtitanium.com.

Builders/compilers are never going to be as good as native SDK. You can save time by using existing BaaS solution for backend but front end you must do yourself and preferrably native.

1. Slowness - where? What was the app doing and how was it slow? 2. Memory Leak - did you pollute the app.js / common scope? Were you killing event listeners when finished? Were you nullifying windows when closing? Were you using CommonJS 3. App size is larger - yes, there will be an increase due to the base libraries used but best to clean the project and rebuild to ensure you're only using what's required for the app. 4. UI is not as cool as native - What does this mean? Appcelerator uses NATIVE controls - you can't get more native than that. How did they not look as cool? - Use CommonJS - Don't Pollute the global scope - Nullify on completion - Ensure even handlers are removed PS. It's possible to write a slow, large app in Objective C that as memory leaks.

We’ve been using Titanium Appcelerator for about 3 years. The short summary:1. It’s buggy. Endless amount of bugs.2. Lazy dev reaction on investigating and fixing bugs. Some bugs are unresolved (and event aren't investigated) for years!3. Poor documentation.4. Poor support. The both community and devs.5. It’s slow.6. It’s not free anymore. However quality of the project is still the same - poor. And yes, it's even more slow now. I’m not sure it is worth paying.7. If I had a time machine, I’d stay away from TS.Also, just several days ago they have closed community support web site. I.e. they have flushed down the toilet “google-searchable” community data accumulated for several years. Unbelievable! Is anyone still paying them subscription fee after that?Also, they delete critical comments in their blog, hiding the truth.So, you should think twice (or even more) before using Appcelerator for production development. We've made a mistake sometime ago and want to warn others.FYI: https://www.glassdoor.com/Reviews/Appcelerator-Reviews-E501855.htm