I write a Sencha 2 app and I test it on Galaxy S with Android 2.3.4. It feels almost perfect. However this happened when tested on Galaxy Nexus with Android 4.0.
I didn't expected this behavior from the most powerful phone on the market. Transitions look really awful, but the toggle/slider thumbs displacement when scrolling is even worse.
Somewhere I read that the flickering is probably due to a CPU to GPU passing for render. This seems to be a major problem that can't be controlled. Do you have ideas how to workaround this? I really hope Android 4.0 user experience will be at least as great as Android 2.3 before the Sencha 2.0 GA.