I have to take care not to blame this book for not being what I was I hoping it would be. I was hoping it would have a bunch of new spells and magic items and really focus on the big-budget special effects style fantasy that is my not so secret preference. Instead, it had a lot of fiddly rules about various niches and corner cases in its various magic systems. We learn a lot about blood oaths and spirit summoning and, good god, entirely too much about spell design, but genuinely new magic is sparse.
It's not all that bad, except for the spell creation rules. There is some value in knowing that evil mages can cast more powerful spells using human sacrifice and what the different types of elementals look like. And the fact that legendary heroes can make magic items by using them for epic deeds was actually a damned cool mechanic (even if we got no specific examples of what this might look like).
The fantasy elements I most enjoyed were the optional Talent Knacks. They're neat little tricks that do things like allow Cavalrymen to summon a flying spirit mount, Beastmasters to grow claws that act as tools, and Archers to fire an arrow that stops right in front of a target's face. The knacks are generally a bolder form of skill-based magic, suggesting a way of approaching Adepts that is reminiscent of (or, more accurately, presaging) the most interesting parts of Exalted.
Unfortunately, I think Talent Knacks are an example of Earthdawn's mechanics writing themselves into a corner. Even the best of them have a kind of ad hoc quality to them, and even though they expand the Disciplines' abilities, these expansions are only really necessary because the default talent lists or so inflexible. This is part of a more general problem with Earthdawn's system, though. Advancing in your Discipline requires investing a lot of your xp into ranking up your core Talents, and straying from the central path will put you irrevocably behind.
I went ahead and consulted 4th edition. Raising your level is a bit more flexible and Knacks are a bit better organized, but the fundamental disconnect remains the same. A lot of core Talents are just more dice for normal skills, with Knacks being a new mechanical implementation for actions that should either be part of the powers originally or just entirely new Talents added to a Discipline's progression.
There are some great fantasy elements. People mine pure elemental fire by flying over lava in their airships and tossing in explosives. If you travel into the astral plane, you are effectively a spirit and can be summoned by someone who has one of your personal items. There is an alternate reality where the Horrors wiped out all life.
However, those spell creation rules are really rough. They're more than 20 pages long, filled with charts and modifiers and a lot of different rolls. Which is especially rough for something that PCs are only going to use rarely, and which could have been handled by simple level benchmarks besides. I was also a little disappointed that all but one of the magic item creation methods was spellcaster-centric, a bad habit that even D&D should have broken years before.
Overall, this was more of a utility book than a setting book, which is not my ideal for a magic supplement, but I imagine that if I started playing Earthdawn 1st edition, I'd get a lot of use out of it.
Ukss Contribution: There's also a bunch of rules for miscellaneous magical phenomena like Familiars and Divination. My favorite was the Death Curse. I liked that it was just a thing that any PC could do, not attached to any Talent or spell. It's not just a great setting conceit, but a great game mechanic generally. The player loses a character, but they get one last chance to chew the scenery, do a bit of last minute dramatic editing of the world, and get a bit of revenge into the bargain. So Ukss will have death curses too.