I was already excited enough for Ravnica, but getting this on this day was basically the best possible. Reading over the guide now, it is very spicy. I love it.
The writeups on all the races is perfect. Warforged definitely give that first read WOW! with their armor shifting abilities, but after actually thinking of the numbers, I am less impressed. Very good if no magic armors exist, but not out of wack. (Though a baseline 22 AC at level 17 is pretty nice for those str warforged)
Changelings are very nice, love the new alter-ego trait. But as a DM I am always warry of letting the players run wild with the shape change ability.
I skimmed the full section on Sharn that they have (Another A+ from me, Sharn is the #1 city in the multiverse, fight me) having run several games there it meets my goals of having information for DMs and these wonderful sections with just ideas for why players are there, what you can do with the locations, stories that might start there. Things that get the creative juices flowing even if you're not just setting an adventure in Sharn or Eberron.
Also, that magic item section. More common items that make Eberron feel like the magical industrial revolution happened. I wish I had that idea for Glammerweave rather than my dull persuasion and perfomance bonus. The writeup on Eldritch Machines as plot devices and some examples. Absolutely beautiful.
I have not gotten to reading the dragonmarks yet, but honestly, this has far exceeded any of my expectations.
I could have lived my life if they never updated Eberron for 5e, I am perfectly capable of using the same places and names and plots as the 3.5 book. And honestly until now I didn't feel the clamor for "Update my favorite setting x" was reasonable, to say nothing of the bizarre vitriol aimed at Ravnica. But if all the settings updates are on the level of this one, I understand wanting more. Frankly, if this is an indication for how they will do their setting books going forward, then I'm even more exited for the Ravnica book than I was before.
Current rating - Things that I have read 9/10 - Still need to read dragonmarks.
Edit: Just started on dragonmarks. They replace subrace for some races or make a new variant//subrace for others. Everyone can start at level 1 with a dragonmark and I love how they did it. So far so good.
Edit2: Intuition dice are granted by the marks to give you a bonus to skills. If you gain multiple instances of intuition on a skill the die size increases. Given that I love the dice chain idea of Dungeon Crawl Classics, this is such an easy sell for me. Love it.
Edit3: And the dragonmarks actually alter your racial score bonuses. This truly makes the dragonmark a part of your character concept. It's perfect.