While free, it was not worth my time. If you want to learn a lot about Server 2012 R2, find another book. This is not because the author is a bad author (maybe a sell-out, but not a bad author). It's because this is largely a long advertisement rather than a book about Server 2012 R2.
The big disappointment is that I thought I'd learn a lot about Server 2012 R2. Instead, I ONLY learned what's new since prior releases (it focuses on what changed from Server 2012... yes from 2012 to 2012 R2... very narrow knowledge). This left HUGE gaps in overall knowledge. Their target seemed to be to increase sales of Server 2012 R2 but clearly NOT to give strong knowledge. For example, I wanted more knowledge about Active Directory. What I got was ONLY that which was new since Server 2012 (in some cases, since 2008). I learned very little.
To the degree that I can detect them, I will not buy these types of marketing books again. It's very disappointing. There are many others that will likely give a lot more.