The adventure is the last real item in the book, so I'll go over that and then address some final thoughts.
"Blood & Lightning" is such a simple adventure that I'm not going to worry about spoilers.
The adventure opens with the party traveling to a location called Boltstrike Pillar. There are three different descriptions of this pillar, based on which of 3 Icons controls it. Which is one of the things that can be decided when you roll your Icon Relationships at the start of the adventure.
Another plot-relevant element that can be determined at this time is which of the Icons is backing the goblins that try to prevent the party from reaching the Pillar. Stats are provided for the goblins, including variations depending on which of the 3 potential villainous Icons is backing them.
Which brings up my only real complaint about this scenario and 13th Age scenarios in general: How much work is the GM expected to do to accommodate the different Icon Relationships? It would be one thing if the GM could roll them while doing their adventure prep and work from there, incorporating them from the start. But it looks like Icon Relationships are rolled at the beginning of the session, once everyone has sat down to play. And this adventure sets an example that the relevant Icon has a mechanical effect, giving these goblins some cool little extra power.
Once the goblins are defeated, the party arrives at Boltstrike Pillar. And depending on which Icon controls the Pillar, the commander and their lieutenant are different. Different names, different career paths, different everything. Not that it matters too much, because they mostly exist for plot exposition.
The goblins weren't supposed to be able to get that close to the Pillar, so divination spells are cast and another group of interlopers is identified in an area called Greenstand. But the area is basically loaded with magical mines that just need someone to say "Shazam!" to set them off. So the party is sent on this mission and provided with a bit of magical kit to help them on their way.
But by the time they arrive at Greenstand, the interlopers have all been slain. The party can do some investigation, but there's also the risk of errant magical defenses going off. They discover that the area was attacked by a lightning breathing blue dragon and its lizardfolk allies. And that dragon is flying towards Boltstrike.
So it's back to Boltstrike for the final showdown. The defenders of the Pillar have been slain or routed, there's a dragon flying around and something magical seems to be going on at the top of the Pillar. The dragon seems pretty dangerous, but the fierce fighting before the PCs showed up has softened it up and made it beatable by a 1st level party.
Once that's done, they still have to deal with whatever's going on at the top of the tower. Which turns out to be the lieutenant performing a dark ritual of transformation. There are stats for him before and after transformation into some sort of dragon monster.
All in all, it's not a bad starting adventure. It's pretty linear, but it doesn't feel constrained.
One beef that I have specific to this adventure is its handling of rewards. After the goblin fight, you are instructed to give the characters an advance. Once you slay the dragon, you level up. There are suggestions that the characters be given magic items at the beginning of the adventure from their Icon Relationships and in the middle when they're hanging out at Boltstrike Pillar, they are handed some of the garrison's magic item stash.
I have 2 thoughts here:
1) It feels like each of these rewards is too big for what is done to earn them. Offering consumable items, like the potions or runes seems more appropriate. Something like a metacurrency would also work.
2) The Tyranny of Fun. It might still be a loaded term in some places, but I'm using it here to mean the idea that the game must continually be "fun." In between cool battles, you get cool stuff and your character gets cooler and more powerful.
Using a dragon as the climax of the adventure actually leans into this idea. Dragons are cool and fighting dragons is fun. Slaying a dragon is epic, and you get to do it at 1st level in your first adventure!
Overall Thoughts on 13th Age
Believe it or not, 13th Age has grown on me a little. It's gone from something that I wouldn't want to play to something that I might play.
Things I Liked
The Combat System: I actually give a lot of props to the combat system. It's designed for Theater of the Mind play and still offers fun options for players. Monster stats are simple and generate interesting results even if the GM is just making an attack roll for them every round.
Incremental Advancement: The fact that there were only 10 levels was a bit of a turn-off for me initially. Making the GM decide when to advance the characters and making the advances so chunky felt like it would be hard to the GM to manage well. Creating multiple smaller breakpoints gives the GM more flexibility in how their campaign is paced.
Things I Disliked
The Combat Focus: I have a lot of respect for a game that knows what it's about and does that thing well. But just about everything outside of combat was either handwaved or a really neat idea that didn't have a solid implementation.
Icon Relationships: This was a neat idea, but like nearly everything else that wasn't combat, it wasn't very well developed. And in the sample adventure, having each Icon give a different combat advantage to the monsters is a neat idea, but signals to the prospective GM the degree of design work they have to do.
No Metacurrency: I admit this is a personal taste thing. But I feel like there were shortcomings in how certain things were addressed that could have been better handled with a metacurrency. Rewards, especially, have the ability to feel very coarse-grained or chunky.
Now for the next question: If you are going to play or run some sort of D&D, is this the kind of D&D you should play/run?
13th Age is a great game if you:
Don't like bean-counting: There's fairly little to manage. There's very little to buy with money past a certain point. There's no XP to grind. Casters don't have to worry about filling their lower level spell slots because they disappear.
Love combat: This is the one area where the game really shines. It's not complicated, but players are sure to have cool things to do every turn.
Prefer Theater of the Mind combat: While other version of D&D can be run Theater of the Mind, 13th Age is really built for it.
Want characters to feel cool and awesome: Your character is going to be kicking butt and taking names right from Level 1.