About performance.. or more importantly "feeling", how does it compare with native iphone app? I.e. does it have a 2 secs lag on everything that is clicked, etc.
My impression- there is still a huge different in the "feeling" of a native app v. a Sencha app. As a "mobile first" developer, I wouldn't dream of using Sencha.
The good news for Sencha is that many companies will prioritize cost/platform reach and a "good enough" experience will be, well, good enough.
At least on Android, it "feels" fast enough. However, it breaks navigation when you use the Back button (in the interface) and the Back button (part of Android).
Not if you use routes properly. I've been able to get the browser back and device back button on android work right for my work.
On "feeling fast enough", let's pick a jquery mobile case, I tried http://www.jqmgallery.com/2012/02/11/sharksfrenzy/ on galaxy s2 (dual core, etc) and iPhone 4s. The list (notice its translucent, and overly decorated) scrolls like snail on the android phone. While it flows very smoothly on iPhone 4s.
A similar list would do better than that on Android if done in Sencha Touch 2.
I don't experience the sluggishness on my Galaxy Nexus in Chrome Mobile Beta (16.0.912.77). It scrolls very smooth (no lag, or jitter), although the refresh button is a little off (square corners on the bottom).
If you are getting a two-second lag on something it is because you are building an application that is blocking on remote assets, not because you are rendering using HTML; there are many native applications on the iPhone (including ones from Apple) that have two-second delays when you click things, and it is because they are pulling information from some API, such as YouTube, to render the content.
As for "feeling", however, there are a ton of little things that are broken: the blue touch highlight sometimes clears and sometimes doesn't (seemingly dependent on the target of the link, not the source), they are doing some silly HTML5 pushState mechanism to mess with the back button incorrectly (specifically, pushing a new state when you go "back" in the UI when that should really pop a state), etc..
The thing that is really freaking me out is that I'm having a hard time figuring out if they are using native scrolling or not (as in, on iOS 5.0, you can just say "this div is scrollable", and not have to re-implement the behavior): the curve seems wrong and glitchy, but they have nailed enough of the actual visual elements that it is no longer obvious to me that it isn't just that they figured out a way to make the native scrolling perform poorly. ;P
In my experience, performance on iOS is fantastic, while Android lags behind a small amount. Sencha isn't quite at the Native speed level yet, although it's certainly close.
Well just remember, you're building your homes inside the browsers, the day Android fucks up or the day apple announces a radical change to their browsers, it might affect everyone. Well for all good reasons everyone has an incentive to improve their browsers so far.
Performance on iOS is superb. Performance on Android is workable - I test regularly on Desire HD and Galaxy S2. Without animations android performance is really usable, even in a heavy app like mine (shit loads of decorations, 3k js)
