I rarely (almost never) run monsters right out of the book, instead taking a statblock and modifying it in some way to make the creature more interesting to me. The Level Up monsters are a lot more interesting, which means I'll likely have to do a lot less modifications in the future. The addition of tables for behaviors and signs also helps to make the creatures more real and gives them a greater impact on the world around them. The encounters table for each monster helps to scale encounters very well.

I will say that a couple of the new monsters in the book, by which I mean the ones that were intended to replace the monsters unavailable due to legal issues, feel a bit lacking. The khalkoi, for instance, has a fascinating concept but not enough is done to make them into a people with a culture of their own (and they're shown wearing rich clothing, so they must have some sort of culture); they feel like one-note monsters. This is the kind of creature that desperately needs an "Ecology of the..." article!

It's great if you want a bunch of NPCs (and you can easily just rename them if you don't want a historical or fictional character in your setting, which is what I plan on doing). However, because these are characters based in real-world history or literature, they aren't overly "fantastic" or magical in nature (except for the few monsters in there, like Black Shuck). In a D&D-type setting, which is usually rife with magic, that makes them fairly odd.

Also, despite what the table of contents says, the warlord Fighter archetype is not a playable archetype. It's actually a list of abilities originally from a warlord (class, I assume), "created by one of the 5e designers." I'm guessing they included that as a way of stating that the abilities weren't their own design. If you were looking for an additional Fighter archetype for your LU game, you won't get it in this book. (Of course, Level Up has the Marshal archetype, which is the Warlord under another name, so you won't be bereft.)

I adore the journeys and exploration section! It definitely made my last session come alive.

I find the system amazing. I've been able to use pieces in my existing 5e game with no problems at all, I can't wait to get my players to make characters in the system, and when I've made characters myself, I find that the heritage-culture-background-destiny divisions help make each character feel alive and unique.

I find the choices you can make for your characters to be extremely useful and flavorful without being overwhelming or leading into trap options, and there's a great emphasis each each class on both the social and exploration tiers. The expanded equipment section provides a lot of interesting and useful items, and the new weapons and armor properties make each of those items interesting beyond how much damage they do or what AC they provide.