[smackfu]

They did announce they would not guarantee source compatibility until after the release date. So the language will likely change a bit still.

[chc]

Huh, I must have missed that. That's definitely contrary to the message most of their stuff is putting out, which is "Go ahead and and use it to write applications." Thanks for pointing that out.

[mitchty]

There is a context you're missing. Use it sure, but be ready for them to change things prior to GA.

This happens pretty often in their betas. First few iterations of even new frameworks can end up doing vastly different things than later versions.

[e28eta]

And promised converters for any source changes necessary. I expect it'll be similar to the Convert to ARC and Objective-C Literals Menu items in Xcode.