I was using it. Loved it at first, put one app into the app store (ifindz), but now totally abandoned it for titanium appcelerator. Reason: mt is too buggy, too unstable. Especially - gc, anonymous methods. It crushes inside binaries, and it's impossible to debug, because presence of the debugger totally changes dynamics of the execution which caused the problem. Also, startup time is noticeably slow, binaries are fat (it carries the whole .net with it) On the positive, though: it is as close to iOS sdk as anything can be, it is complete port. When making decision about moving to titanium, 2 things made the choice easy: -- JavaScript as a language; -- now I can alter my native apps just like web pages - on the fly, at any time. Can't beat it, especially considerin app store's approval process. As a result - my app written in titanium (iwakeapp) has been finished in a fraction of time it took me to fight through mt. Hope it helps. Good luck.