The new book is not unplayable, but I acknowledge there's a fair amount to hate about it.
Troglodons are not just useless, they're also a mess in general. They're supposed to be blind, but they have a BS based shooting attack? He supposedly lives underground, and maneuvers carefully by using his whiskers to feel out where he's going, so of course he should run around in open fields at M7? The other lizards are all afraid of it, so hearing it roar inspires your fighters to greater heights? Seriously, what the heck is wrong with this thing? It's a waste of points and a flavor mess.
There's a ton of really sloppy rules. Is Predatory fighter meant to work with supporting attacks or not? Why is a Slann worse than a Skink at reigning in your Predatory fighters? Shouldn't Skink characters on Rippers be able to join Ripper units? Speaking of which, do they get to place / take advantage of bloat toads? Is it intentional that supporting attacks can't hit Krox in a mixed unit? Do the special AoE spells found throughout the book ignore the "in combat" restrictions from the BRB? How does the Egg of Quango work in a challenge? When multiple Salamanders fire, how are the shots resolved (sequentially or simultaneously)? Does the Piranha Blade really give the character in general the Multiple Wounds (D3) special rule, instead of just attacks from the Piranha blade? The answers to these questions have a major impact on how lists are built.
Cold One Riders can't take a magic banner? Seriously, for all those points? Inner Circle Knights cost 9 points less per model, are Core, aren't stupid, come with a 1+ armor save and lances, can take magic banners, and can swap in great weapons for free. But I have to spend 4 points a model just to get spears?
Whose bright idea was it to give Kroxigor a bunch of special abilities that only function in the first rank, like Stomp and Predatory fighter, when they always fight from the second rank in mixed units? And then just to rub salt in the wound, change it so they're not even protected from attacks by being in the second rank, just in case you thought there might be some reason to do this? It's like someone really, really hated Skrox blocks, and wanted to ensure they were as terrible as possible. Saurus and Skink Skirmishers for life (apparently).
The list goes on. There are elements of the book that are still powerful, so it's not unplayable, but an unfortunately large amount of it is sorta depressing. It's not nearly as well constructed or as well thought out as many of the other recent book updates.