MANY green flags going into C4 with this first episode, at least for my personal taste.
The clear weight of history already hanging off this world and these characters was absolutely the correct way to go, both for the purposes of not having to see thirteen characters all get to know each other, but also for emulating the epic fantasy genre they're going for à la ASOIAF/Stormlight Archives/etc. Personally, the vibes I'm getting are very Jade City, which is absolutely a compliment: we start in a world that's already had a whole other series' worth of world-changing events occur in the fairly recent past, events which our characters/their families and associates are all tied up in, but the new world that arose from those events might be even more complicated than the one before, or at least complicated in a way that the heroes and descendants of the previous era don't really know how to approach or manage. I'm not sure if C4 is going to take a similar tack, but it certainly doesn't hurt it that that's the book series I think of right off the bat.
Most of the characters being middle aged and older leaves so much room for long-lived, messy dynamics that you just can't get out of younger characters, like Hal and Thaisha's complex romantic history or all the old war buddies who have already been through so much shit together. Whatever conflict the campaign presents, there's no need to question why these people are going to be the ones stepping up to meet it; clearly they've already handled a lot in the past, and the personal connections seal the deal.
Thjazi Fang is so wonderfully interesting as an inciting incident and (mostly) posthumous character. Everything we know about him gives Protagonist, but we're telling a story that starts with his death. There's something so fascinating about stories that defy convention by punching a hole where the character that is clearly supposed to be at the forefront and leading the charge should be, leaving the side characters around them to step up and fill in the gap (again, without getting into specifics, very Jade City). Fantastic premise to start a D&D campaign with.
All the characters are great. Thirteen whole dudes and not one of them was a dud. Even the ones who got fairly little screen time like Thimble, Kattigan, and Vaelus had incredibly strong intros, and the quieter characters like Hal and Azune leaned in hard to their deep connections to their fellow characters and the world and history around them. I've known these guys for one session and the grief and confusion and anger they're feeling at this monumental shift in their world (plus whatever the fuck is going on with Julien 'It's giving Jaime Lannister' Davinos) is palpable. Incredible stuff, no notes. I'm only sad it's not feasible to keep them all at one table all the time.