Reddit mentions of Cisco IOS XR Fundamentals

ASR1k? That runs IOS-XE. IOS-XR runs on ASR9K, CRS, and XR. Cisco Press has a book on IOS-XR that isn't awful. The docs on Cisco's site are pretty decent actually.

http://www.amazon.com/Cisco-IOS-Fundamentals-Mobeen-Tahir/dp/1587052717/

http://www.cisco.com/c/en/us/support/ios-nx-os-software/ios-xr-software/products-installation-and-configuration-guides-list.html#anchor2

The most difficult thing for me was understanding exactly how to apply RPL to get what I wanted. The If/then/else thing is pretty nice but can be a bit cumbersome. You can't just "insert" policy at any point like a route-map or juniper "terms". You have to re-apply the whole policy or edit it interactively in the online editor.

There's also this:
http://www.cisco.com/en/US/docs/ios_xr_sw/ios_xrv/install_config/b_xrvr_432_chapter_01.html

Something like this?

http://www.amazon.com/Cisco-IOS-Fundamentals-Mobeen-Tahir/dp/1587052717