There is a number of folks that have been writing about Astoria. Collectively they built a lot of reference material that is probably the best reference point for getting started and learning about practical aspects around creating and using data services with the Astoria framework.
Mike Taulty is going for the low-level details and analyzing Astoria clients and servers in and out.
There is much more out there, just highlighting a few. So if you were looking for some reading material for the holidays, there is plenty out there 🙂