It's more The Talos Principle II!

If you liked the original game, you will certainly like this expansion.
The one downside is that it mostly expands a bit on the ideas of the main game in various ways (both the mechanics and philosophy), but doesn't really bring much new ones.

Still, some of these ideas bear repeating. It didn't disappoint, I had a good time!

(contains very light spoilers)

Pure insanity.

Stephanie Sterling put it really well:
"It's like somebody told the dev team this was the last videogame that was ever going to be developed for the rest of time. So if they had any ideas, they better smoke 'em while they got 'em."

Rebirth is a game of variety. Every new areas brings its own unique mechanics and minigame. And they never feel stale, or like they are playing it safe, with completely new ideas all over the board.
Are any of these perfect? No, a lot of them are pretty janky. But even I get to a bit that's kinda "meh", I'm still so happy to see that they Really tried, all the time, everywhere.

While still following a pretty linear story, the game feels more open than Remake. With several open world areas to explore, encountered progressively through the story at infrequent intervals (here too, the game feels unpredictable).
I was initially worried that those ares would end up feeling too much like I was just going mindlessly from one point of the map the next... And I was only half right. I was at least able to grow in familiarity with each area over time, which honestly felt really nice. In that way, I do feel like the game gets a lot better if you limit your fast travels to a minimum... Here, the summon crystal are what feel the most out of place. It really feels like you're just going to some random place for the purpose of pressing a button and just moving on your way. Even with the small blurb of story you get for each summon, they end up feeling quite detached from the world and its lore.
I really like the part near the end where all the various areas end up getting connected into a single seamless open world, although it had the unfortunate effect of also making the world feel a lot smaller. You can compare that to old FF world maps which manage to keep a grounded scale, by showing the world maps in a different style than the rest of the exploration. But I don't really know how they could have implemented this and kept the full realism that FF7 Re is going for.
I also wish they did a bit more ocean exploration.

That dedication to being all over the place sometimes works against itself when it comes to telling its story. Some really serious moments get immediately juxtaposed to silly one in quite jarring ways. You have some truly evil characters also being depicted as aloof in ways that leave me confused as to how the game expects me to feel about them. And the environmental message of the game feels weird juxtaposed to the great show of playfulness that is the Golden Saucer, which is itself shown to be very destructive on the environment.
Even here though, this mess isn't all bad. The way the party jumps from adventure to adventure somewhat reminds me of old hero tales, where the idea of the story are more episodic in nature, seeing how the hero will handle this new situation they find themselves in. And FF7 Re is very much a character driven story.
And what character they are... I can honestly say that I love... most of the character of the main cast. Of the main party, there is only Yuffie that I only like instead of love, and even then, she still had scenes that touched me deeply. Outside of the main party though, I really dislike Chadley, which is unfortunate since it's one of the (if not The) biggest ally that we have outside the party.

As a final note. The game also features an amazing soundtrack. I had to stop on several occasion just to take some time and listen to the ambient music. Although I don't think this soundtrack is used super effectively, I wondered on several occasion, uh, why would they use this character's theme Here, when they don't really have any connection to this place?

Now... What comes next? Really... The whole ending chapter had me feeling all kind of ways, and I once again have no idea what will come next, and Rebirth taught me that having any kind of expectations would be pointless. So I'll just wait and see, it's going to be a long wait until the final element of the trilogy.