Lizardfolk
Let me talk about the Lizardfolk section for a bit: I'm planning to use some lizardfolk in my next campaign set in Dangerous Jungle of Lenap in the Wilderlands of High Fantasy. I was inspired by the giant wasp riding Dark Talon lizards from Monster Manual IV and was looking for some more background. That's when I turned to the book we're discussing.
I really liked the intro art – a lizardfolk village behind a lake with wooden catwalks leading up to it. We see reeds, birds, smoke, lantern light, and the orange brown of dusk. And the text says that lizardfolk have "an extensive oral tradition" with "rumbling epic poems". I really liked that part. And I liked how the "wellbeing of the next generation" is very important to all lizardfolk. That was a nice take. And it fit so nice with the ecological constraints: They are diurnal creatures and spend nights "holed up in easily defensible positions."
Clearly I will be having two lizardfolk tribes. One of them peaceful, the other taken over by greed. But even when talking about greed, the lizards will be articulate storytellers, so I'm hoping to add some non-combat depths to encounters. Their positive sides mentioned in the text will also allow me to add more flavor ("fierce and proud, loyal and sober, and if they are quick to anger they are also quick to forgive").
I like the backstory of loss – always slow in comparison to mammals, they retreat further and further into the swamps. This could lead to a Heart of Darkness situation; another adventure idea. Even without such a dark touch, "a culture in decline, a reclusive race of staunch traditionalists uninterested in the fast-moving pace of human society" can provide a nice backdrop against the constant warring between other cultures. Here in the swamps, none but the lizardfolk rule, and they are not interested in the fickle nature of man.
I also liked some elements that are easy to add to a game and still show how alien they are: Their cannibalism ("meat is meat, and squeamishness is a quality better left for the softer races" -- hah!), the combination of trial by (non-lethal) combat and their communist nature ("anything you can't keep by force was never yours to begin with"), or a specific element of their shaman cult ("curing diseases by transferring them to animals which can then be ritualistically slaughtered").
As for editing, I felt that there was potential for tightening up the text a bit. The eggs, the care for them, the defensive value of their settlements, it all comes up two or three times. I would have loved an illustration showing lizardfolk and dinosaurs or lizardfolk and nagas instead.
So all in all, I've found the lizardfolk chapter to be very inspiring for my own game.