Sproutcore had lots of promise, but it seems really to be struggling. Biggest issues (that everyone has known for some time) is the huge learning curve, lack of training materials / docs, and really clunky default ui. I was really sad to see Erich Ocean's book proposal fall flat. Just seems like Sproutcore as a dev community is on its last gasp.
I've recently been ramping up on ExtJS and Sencha Touch. Licensing issues aside, Sencha seems to be spending their time on producing good demos, sample apps, videos, and fostering a solid user community behind it. The tech is actually pretty decent as well (though sproutcore had much greater potential I think).
Amen: I really want to like it, but found the documentation completely impenetrable. It doesn't help that there's a big refactoring effort underway, and the entire views system seems to be changing to Template.
I wouldn't write it off already though: the team knows that the documentation is an issue, and there's definitely a push towards improving it. http://guides.sproutcore.com/ for example.
In Chrome 10, I can't get greenhouse to load any of the projects. In the family tree demo, clicking Add for Male, Female, or Pet doesn't seem to do anything. Trying to open outline hangs the demo page (and I can't then load anything else in the demos page without refreshing the page). Sorting by clicking on column headers in the table_view demo doesn't seem to work (maybe that's not meant to?).
Got family tree to work, you've gotta click the plus sign to create a family, then click on the family to give it focus, then the "Add Male..." stuff works.
As a point of pride I don't publish broken web resources, so it's disappointing to see that they still lack any kind of progressive enhancement support and don't seem to be working on it.
SproutCore, as its homepage states, is meant for "desktop-class web applications," not sprucing up static content. Progressive enhancement is meaningless for this. If you don't have javascript, the web app simply won't run. Accessibility is still an important consideration, but that is a distinct concept.
Principles are important, but principles divorced from context is dogma.
Consider something like GMail. For all those who have an unsupported browser, they have basic HTML view so that you are not locked out of your email on an old browser. The bells and whistles go to users who can use a decent browser.
It is far nicer to think of a basic HTML minimum viable app and an app with a desktop like experience than thinking of gracefully degrading each feature of your app.
I've recently been ramping up on ExtJS and Sencha Touch. Licensing issues aside, Sencha seems to be spending their time on producing good demos, sample apps, videos, and fostering a solid user community behind it. The tech is actually pretty decent as well (though sproutcore had much greater potential I think).