It's difficult to screw up a concept as elemental as the monster book, though Creatures of Barsaive may have found a way. It tells us about 50 of Earthdawn's most unique and dangerous monsters, but it does so with an unreliable narrator who has significant biases, gaps of knowledge, and an unspoken agenda.
Now, this isn't something that ruined the book or anything, but the Kraken entry was written from the perspective that the Kraken was clearly an urban legend and could only be described in hypothetical terms, only for the OOC rules text to just directly come out and say the narrator was wrong and Krakens do exist. Hey, Creatures of Barsaive, I can assure you that the Kraken was interesting enough on its own - you didn't need to waste my time doing a bit.
But then again, look who's talking, right? Most of the time, the conceit that we were learning about these monsters from an arrogant dragon was, at worst, distracting. Sometimes, like when Vasdenjas reminisces on the deep friendship he had with a manticore, it's actively delightful. Still, I think they went to the "the best strategy for dealing with this foe is to fly overhead and roast it with fire" well a bit too often.
The book's titular creatures mostly follow the Earthdawn pattern of well-thought-out worldbuilding combined with so-so rules. In terms of monster-design technology, it's roughly equivalent to the AD&D Monstrous Manual - A standard block of statistics and one or two unique tricks that mostly require GM roleplaying to make memorable. Sell the basilisk's instant death attack well enough and maybe your players will think it's a fun challenge instead of a cheap move.
One thing that Creatures of Barsaive does that I wish was standard in rpg monster books is to end each entry with an adventure pitch. Most of the ones here are pretty boilerplate - gather monster parts for a wizard, drive off a monster that's attacking the town, etc - but the idea is solid, and occasionally pays dividends. Escort a scholar on a doomed expedition to prove the vicious flying worm monsters are intelligent. Join up with a group of ork bandits and learn to tame the weird mammoth-creatures they ride.
Overall, I enjoyed Creatures of Barsaive, but it undeniably puts style ahead of substance. When it's talking about novel, specific creatures, invented especially for Earthdawn, it does pretty well as a monster manual. But it often struggles when it comes to depicting its public domain creatures in an interesting light. Before the Scourge, manticores were good, but for unicorns, it's the opposite. Nobody knows why and the dragon doesn't have any theories. So it's like, okay . . . good to know.
Also, the Wyvern entry is weird. Shadowrun does the same thing - get a dragon talking about wyverns and they get all defensive and vague, in the way people sometimes do when they're trying to deny a crime they're not sure you've discovered. "Wyverns are not dragons. They have never been dragons and they never will be dragons." Um, okay. It's a coincidence. So why follow up with "Never suggest otherwise to a dragon, unless you want to end your life as a lump of charcoal"? What are you hiding? Oh, we're moving on? Because this is a bit of secret metaplot destined to never be resolved? Got it.
But mostly Creatures of Barsaive was okay. It had a lot of entertaining ideas. Like a species of magical rat that rides larger creatures and mind-controls them into hunting food for them (although it seemed to me that sending your host into a berserk rage and then feasting on the corpses of its slain enemies would provide entirely too much food for a single rat-sized creature.) Or magically corrupted faerie creatures than have the power to telekinetically reshape bones . . . even while they're still inside a living creature. It's an imaginative, useful book with the unfortunate tendency to waste a significant part of its wordcount building up the narrator's characterization.
Ukss Contribution: The globberog is a disgusting, cow-sized land-mollusk that secretes a powerful glue, which it uses to attach dead bodies to itself, both as a sources of sustenance and a form of protective armor. Over time, it become a huge mass of decaying corpses, so large it can no longer move. When that happens, the adult globberog gives birth to a bunch of babies who eat the corpse pile from the inside out. And the cycle begins anew.
Gross as hell, but memorably distinct, with just a ring of biological truth to it. A good fantasy roleplaying monster, in other words.