What do you like best?
Appcelerator is a great cross platform tool, I love the fact that it uses native elements instead of reinventing the wheel, its fast to create an app once you get to learn it and maintaining one code base works really nice for me. Overal its a fun coding experience and I still use it today.
What do you dislike?
There are many bugs that are there for YEARS and still haven't been resolved and I don't think they ever will be resolved.
Many core features are still missing to this day and you have to rely on unstable, undocumented and unmaintained community code to do stuff that should be part of the main sdk.
There ARE memory leak problems that can be resolved with hacks (and I don't like hacks, I like clean and out of the box ways of dealing with my code).
To me it seems that the community is almost dead (most of the answers and questions you find are 3-4 years old).
The feeling I get is that the company tries a lot to keep up with Google and Apple in implementing new platform specific features and invests no time at all to update/maintain the existing code, in order to make it more robust or even implement some CORE features that are still missing.
Recommendations to others considering the product
Appcelerator is not an one size fit all tool. Use it only for projects whose features are fully supported. Make sure that the community had no problem using the features you wish to support before you step into it because there are many cases of simple features that people using appcelerator still have a problem implementing.
Also I wouldn't trust appcelerator performance wise neither would I trust its community to get an answer to my question in time. At least not if I'm not paying for an enterprise subscription to get a quick answer directly from appcelerator, which I'm not doing at the moment.
I guess my suggestion is use it ONLY when you're absolutely certain its right for your spesific project. As most tools it has its advantages and disadvantages.
To me though, and thats totally a biased and personal opinion, appcelerator feels like it had its moment in the past, but is currently dying. I would gladly switch to another tool if it offered the same features in a more robust way and with a bigger community.
What business problems are you solving with the product? What benefits have you realized?
When I'm in charge for very simple projects I almost always use appcelerator. It's faster for me to make a working app with it than with anything else.
I have to be absolutely certain though, that the app won't receive any important updates in the future, and that I will not have any more complex feature demands for my app later on, otherwise I might get in the trouble of wasting too much time reinventing the wheel on features that other platforms already support.
I've spent so many hours in gitt.io looking for a third party module because appcelerator did not implement it as they should.