I was starting to lose hope when Alpha 5 came out, and was despondent by the time Alpha 7 did. I'm plugging along with the book, half way through the first draft, but at least 25% will need to be revisited to complete examples that hit brick walls because of things just not working as they should, yet, such as custom fields not appearing in the Views sort criteria field list.

Migrating from Alpha 7 to Beta 1 was not for the faint-hearted. I could have attempted to use Head2head, or the Migrate module, but both required considerable overhead and I needed to move the dozens of content types, nodes, blocks and views onto the beta db sooner than I would have been able using either of those methods. Instead, I diff'd the two schemas, so that I'd know if there were issues with any of the populated tables, and went table by table, importing what I needed to (nodes, blocks, custom fields, etc.), ignoring what I didn't need (cache, watchdog, etc.) and tiptoeing through the mixed tables (those populated with a mixture of default data and custom data, leaving behind the default data in case the new default data was different).

From this point forward, the updates should be doable in a standard way. I look forward to that, to the eventual release, and the book being done!