Comparing the documentation of DirectAccess for 2012 with other products, even DirectAccess 2008, I see that it lacks some in-depth insights that an Admin needs to be able to deploy and manage the component effectively.
for example, I could not find a TechNet article describing in details, what happens from start to finish when a resource is being accessed through direct access:
1. how is the NAT64 working? how does NAT64 translates address and which IPv4 address translates to which IPv6 and vice-versa? how does the component come up with those connection security rules in GPOs based on admin input in the config(which configuration part has affect on which GPO setting)?
2. manage-out. how does that work and what are the caveats?
3. the lifecycle management: how do you migrate from 2008 or UAG to 2012 and eventually 2016? how do you manage expired certificates or swap of the root certificate without the client down time?