Been using Titanium for a little over a year on an app for our company. By all definitions our app is very simple - a login form, tableviews that drill down two levels and webview.

Our customers like the app and it works great, does exactly what it's supposed to do. iPhone development seems to go pretty smoothly. Debugging is fast. On Android it's a nightmare. The emulator is so slow to launch for one thing. It reminds me of developing a site and then when you're all done, testing it on IE6 and, surprise, nothing works! That's been my experience anyway.