Argh. Can we blame WotC? IMO there should be a special circle of Hell for graphic design people who over-decorate the page, at a serious cost of readability. They used the fake-parchment coloration on every page, a la most of 3E and 3.5. Always hated it.
That off my chest...this is somewhat interesting. This strikes me as largely deep-background material for GMs and world builders. There are several different sections:
--Essence relates to magical energy in a physical form. It's a useful concept, but IMO not sufficiently developed. Then again, I've spent considerable time thinking about a 2-tiered economy...mundane items and magical items.
--Ruling a Domain...think kingdom, not divine domain. Large-scale stuff. Seen these kinds of rules before, I don't really recall anything that stands out.
--The Multiverse has one novel, interesting section: the magical and technological advancement. It outlines different approaches for both spellcasting and item crafting; Renaissance crafting, for example, offers the notion that items can be reasonably common, and used by most. It includes integrated magic and tech as another set of conditions. This section's not so much usable on its own, but as a jumping-off point for thinking about the societies that can be built. This is "take off your blinders" stuff, if you've been limited to just D&D.
--Immortals...hm. My closest take is Ascended beings, a la Stargate, but also crossed with elder Camarilla vampires from V:tM. One of the significant values of this section is to point out some of the flaws with the typcial busybody-gods approach...Forgotten Realms is notorious for overdoing divine interference. There is some cool stuff; the spells have scope that's often lacking when discussing this kind of advanced magic. I think this is best used as a basis for thinking about your own gods, and how to handle them.
--Chronomancy...I detest traveling back in time in a way that allows a complete historic re-write. They do try to talk a GM through some of the issues like the classic "kill your grandfather" paradox.