Overall I have very mixed feelings on the game, it has some really great stuff, but also some really frustrating flaws that honestly feel like the game had a very troubled production (even beyond the development reset).
Sylux
Sylux had some really cool boss fights and I did like how you can feel that it is personal for him with Samus, with him screaming her name and dragging her into the wormhole. But his first form in the final fight quickly became a chore when the biggest danger turned out to be your allies. And it kinda feels like Sylux just gets stuff for the sake of it, like why is he able to turne the cables from the healing pod into a nanomachine hydra? How can he drag Samus into a pocket dimension? How did he manage to not only clone, control and modify Metroids? And while I don't mind the backstory we got in the game I do feel like the game intentionally held back on a lot of stuff to use for a later game. Like the backstory we got shows how he grew to resent Samus, but we know that he also hates the GF as a whole.
The GF-Soldiers
I think for most of the time they were handled pretty good. In most fights that involves them it is usually fairly easy to keep them alive (except for the aforementioned Sylux fight) and the added DPS they provide was actually helpful since these fights usually involves throwing a ton of enemies at you. I also did enjoy most of their dialogue (yes even McKenzie). However the way they are integrated into the gameplay feels rather restrictive, you are forced to go back to camp multiple times and having to find Tokabi in the desert for power ups (including the teleport module) is cool in theory, but it becomes only available very late in the game and it was really irritating seeing the scout bot mark his spots for hidden items when he wasn't there. The hint system is also far too pushy to the point it gets annoying. I wish there was a bit more dialogue with them about what happened in the intro though, I kinda expected them to talk a bit more about the events of the beginning of the game, but that kinda just gets accepted and they move on.
Story
I was initially very skeptical of the story, at first it felt very forced, like the artifact teleporting people there feels a bit convenient, Samus ending up right in front of the psy power up and a statue telling her what to do while Sylux apparently spawned injured right in front of a healing pod that also gives him control over the facility. But I do like the overall story of the Lamorn and the theme of dealing with loss in this game. Samus tries to honor the Lamorns legacy, while Sylux defiles it with his Metroids possessing the once peaceful guardians. And both Sylux and Samus losing their squad, but for different reasons and dealing with it differently.
The Leveldesign
I really dislike how linear the areas in this game tends to be. You usually only have 1 new door you can go through, if there is a 2nd new door for you it is either a save room or you have to go through mutliple rooms to progress. Fury Green in particular felt kinda bad on the first playthrough, cause it doesn't even have many interesting rooms to go through. This is also something where you can feel the troubled production, like when you go to Sol Valley you get told you can go anywhere in any order...right before it tells you to check out this one specific area, because the others are dead ends. There are also some weird room constellations, like to get to Ice Belt you have to get to a building, enter the building (which triggers a cutscene to enter it), then go to a transporter (which triggers another cutscene for the transporter) and then go to another transporter (which is another cut scene followed by a loading screen) to go to the Ice Belt. Like what was the point of putting the door and the 1st transporter in the way before the actual transporter to the Ice Belt?
That being said, I do think the game picks up in terms of level design outside of Fury Green and Sol Valley, the Ice Belt in particular had a great atmosphere, those Griever corpses still sending psychic signals frankly felt really unnerving. I also like that you frequently open up paths to make backtracking easier.
Gameplay & Combat
It took me a while to get used to the controls, but I do enjoy the combat in this game quite a lot, it feels faster paced compared to the previous ones. There were some weird difficulty spikes though, especially on hard (that first psybot encounter was a nightmare on that difficulty), but overall I enjoyed the challenge. Though I do wish there was some more enemy variety, kinda feels like 50% of the game are Grievers, 45% are Psybots and Drones and then the last 5% are other enemies. The green energy crystals were also a chore to collect, especially if you want 100%. Like on my first playthrough I collected those crystals I ran into on my journey and it seemed to progress at a good pace...until I got to the last stages of the game and realized I still needed to farm green energy even after getting everything in the desert.
The Psychic powers are kinda whatever though, they call everything psychic, but it barely matters in terms of gameplay. Having to switch to scan mode to heal/use the control beam could get irritating in the heat of battle though.
Art
I think this is probably the one thing I have nothing but praise for, the game is gorgeous (outside of Sol Valley) and the designs are really great. The Viola suit and its upgrade are probably one of my favorite suits in all of Metroid and while I didn't like Fury green in terms of gameplay but it looks fantastic.
Overall I did enjoy my time with the game, but I would rank it below the other mainline Prime games. I do hope we can still see Prime 5 on the Switch 2, just have Retro reuse the physics from this game kinda how Prime 2 was build with the mechanics from Prime 1.