NO SPOILERS
I played Waking the Past at low subtier using the four-player adjustment. Without having read any other reviews, my guess is that the scenario is one that people either love or hate. It has a particular gameplay mechanic that some will find pretty cool and exciting, while others will find it grossly unfair. This is a scenario for truly intrepid explorers only!
SPOILERS
I really like the backstory to Waking the Past, even if it's very reminiscent of the background of the antagonists in the classic Star Trek episode "Space Seed" (yes, the prequel to . . . "Khan!!!"). A group of pre-Gap extremists on Golarion were forced off-world for their views on human genetic purity and violent attacks on non-humans. This group, called the Twilight Throne, were powerful magic users and skilled scientists, and established new bases on a planet in Near Space called Thosum V. In one of these bases, an experiment to create a nanotech golem went very, very awry, as the creature eventually killed every sentient lifeform on the planet before returning to a state of hibernation in the base.
What the PCs in the scenario don't know, of course, is that they're headed to explore that particular complex. The story starts with a solid hook. AbadarCorp miners on Thosum V uncovered a sealed complex miles underground. Pursuant to their contract with the Starfinder Society, they've notified the group for an exploration team on the usual terms (the SFS gets historical insight, AbadarCorp gets any new technology or equipment). Venture-Captain Arvin delivers the briefing, and I like how the scenario establishes his prior connection with the elf overseeing AbadarCorp operations on Thosum V. The two are old friends, and cooperation is the order of the day (reverse foreshadowing some difficulties in the epilogue).
The journey from Absalom Station to Thosum V takes place aboard an AbadarCorp freighter. There's a brief mention of a character who is apparently important for a future scenario, but very little detail is provided. I tend to think these little bits turn out to be more frustrating for the players than exciting little easter eggs for discovery, and that it might be better to just start more scenarios at the mission site (with a briefing given remotely) than requiring a hand-waved trip every time. Another bit that's a little off in this scenario is that the scenario tells the GM the journey takes 3d6 days of travel through the Drift (the standard for a journey from the Pact Worlds to Near Space), but the ship also just so conveniently arrives (no matter what the dice roll is) during the five days of Goldfest, a big celebration on Thosum V. It would be better for scenarios to dispense with the "3d6 days" fiction and just tell the GM how long the voyage takes if it's plot-relevant (which it hardly ever is).
Anyway, there's a good little scene when the PCs arrive as the local miners think the Starfinders are going to shut down the dig and hurt the economy. This could have been fleshed out more, and would have given some additional opportunities for role-playing in a scenario that has very little. We also don't get to see much economic angst in Starfinder scenarios despite some of the setting themes of hyper-corporatization and limited social welfare programs. Anyway, the PCs do get to have a conversation with the AbadarCorp leader, Taxmaster Alazdra, but that's really not much more than another briefing.
The first encounter is original and fun. As the PCs are taking the lift down the miles-deep shaft to get to the complex, they're attacked by burrowing pests. After just a couple of rounds of battle, the fragile shaft will start to collapse, raining down rocks and threatening to crush the PCs unless they get out of there fast. It leads to a classic situation where the PCs are trapped underground with no obvious way out, which helps add to the tension of their exploration of the complex.
So, the complex: one thing in the scenario's favour is that, although this might at first glance seem like a traditional (space-) dungeon crawl, it's really more like an 80s slasher pic. There's an incredibly deadly, implacable adversary that seems invincible, and the only thing to do is run, hide, and hope to stumble upon a way to escape. Instead of a Jason or a Michael Myers, the slasher's role in Waking the Past is played by the aforementioned nanotech golem. This thing is CR10, has a +27 on attacks (doing 4d6+20 points of damage), is immune to almost all magic, and has regeneration 10 to bolster its 250 hit points. In short, its effectively unbeatable for PCs of either tier here. The concept of the scenario is that the PCs should quickly realise they have no hope of defeating the golem and should instead keep moving, exploring the complex as they go, desperately hoping for a way out. I think it actually works out pretty well, though I imagine many groups learn the hard (TPK-oriented) way that not every enemy is designed to be defeated. In addition, it's really important that the GM carefully read the monster's abilities, tactics, and the two sidebars about when it appears and how it operates. There's a lot of information to process here, and I wouldn't recommend this scenario for a novice Starfinder GM. I guess if nothing else, it does help that it's *really* hard for a PC to actually die in Starfinder due to the generous resolve point mechanic.
Apart from the nanotech golem, the complex contains a few clues (on cliched "one entry only" datapads) about the scenario's background, though the PCs won't learn much about the Twilight Throne or the fact that this golem wiped out all life on the planet. There's also a trap or two, the usual security robots, and some undead to fight, though the PCs need to be careful not find themselves stuck in an encounter when the nanotech golem catches up to them. The main goal is escape, and to do that the Starfinders need to push open the stuck "back door" of the complex which then leads to a long tunnel and the surface. I'm don't understand why the golem won't keep following them up there (given what it did in the past), and arguably the more "heroic" thing for the Starfinders to do would be to trap themselves in the vault with the monster to save thousands of lives on the surface. But, that's a digression, I guess.
The scenario has a potentially interesting epilogue, where Taxmaster Alazdra leans on the PCs to keep their discovery secret lest it interfere with profitable mining activities that employ hundreds on the planet, despite the incredible danger. The PCs can decide whether to reveal what they learned to the world or not, with some consequences for boons. I always like good moral quandaries to bring out role-playing.
As a quick side-note, I will say I really don't like the new art style for Season 2 scenarios.
Overall, I had fun playing Waking the Past, but I imagine it could be a quite divisive scenario. By the time the players figure out what they're supposed to "do" (run!), it may be too late. In addition, some of the scenario's flavourful backstory won't really come across to the PCs. On the other hand, I like to see different gameplay concepts, and experimenting with something different than dungeon crawling is a plus in my book.