For someone who misses templates from 3rd edition and feels 5th could use some more, this book has 10 new templates: Angelic, Clockwork, Fiendish, Formorspawn, Ghostly, Krakenthrall, Riftwarped, Topiary, Vampiric and Zombified.
Additionally, most of the templates come with optional components that let you customize the creatures you create further. For example, Angelic has "Divine Blessing", which lets you pick one of four abilities. Each template comes with a pre-templated creature (the aforementioned Angelic is an Angelic Half-Ogre).
Overall, the templates that made the most sense (Angelic, Fiendish, Ghostly, Vampiric and Zombified) were ok, giving me exactly what I would expect when making such a creature. Clockwork is great, turning a creature into a construct. Formorspawn is ok, focusing on the Formorians and their allies becoming sort horrible monstrosities but we have plenty of those so I can't see using it. Krakenthrall I like in statistics but from a narrative it's odd. I feel like maybe it'd be a good warlock patron but regardless it is still statistically viable. The far realm rules the riftwarped (why not "Cthonic"? I'm not sure) giving you weird lovecraftian nightmares. Finally topiary gives you plant creatures.
Overall, great book and one most DM's can use.
[4 of 5 Stars!]