I loved the game. Several people complain that the protagonist talks a lot, but only when compared to dude (who's name I can't even remember) from Subnautica 1. She's spunky and it helps the game from being as lonely. The two burning questions from when you start don't really get fully answered, as the story/ motivations takes a 90° turn in the first third, and I'm okay with that. Oh and despite what people say, it's maybe a quarter on land at the most (I didn't build a single thing on land other than beacons and the vehicle thing I won't spoil).
If you enjoyed Subnautica 1, get this game. I found it even less scary. It's a full game, but started as DLC so it's technically a smaller map (feels denser to compensate). Subnautica 1's map was so big that I found out at the end how I'd somehow skipped 2 whole biomes by pushing my luck. The new vehicle(s) and wildlife are both weird and fun. I played on "Freedom" difficulty to avoid worrying about food and drink, and am glad I did. I did the whole food+drink rigmarole in Subnautica 1 to prove I could; half way through you solve hunger+thirst and it's just a nagging issue taking up slots. No achievements are tied to difficulty, and they never soft lock out (game explicitly tells you when you hit the end 'point of no return').
Waiting a year and a half since finishing Subnautica 1 was definitely the right call, this game just scratched that itch nicely without getting too long. They made some attempts to help guide you through with series of flashing lights or single HUD markers for *some* content, but if you're min/ maxing for achievements, videos on the locations of things do help. I really wanted all the fragments/ upgrades, and even with guides it was challenging at times.
Anyway, I always give tips in my reviews, but mostly assumes you know Subnautica 1 gameplay:
Still only has the one save slot, so save often but only when you know you're truly safe. There's no point to playing Hardcore difficulty, in every other mode dying will only cost you almost everything you've gained since last exiting a vehicle/ base (it will randomly keep 1 item). The dropped stuff possibly falls where you died, but rolls away pretty quickly.
You only need one main base (Twisty Bridges) and just build it near the surface. Be sure to start it with platforms for way more stability than you think you'll need (because you will).
When an item is in your quickbar, use R to swap batteries (save the dead ones, you can recharge them eventually).
Hold off on guides as long as you can. F1 to see coordinates on your screen... they are in the order of: East is positive, Depth, and North is positive (in that order).
Scanning rooms are OP. You can make mini-bases that are a multipurpose room (with some kind of power generation) connected to a scanner room. Know that scanner rooms can only connect on one side, so if it's refusing to place scroll up/ down to rotate (also look out for yellow things blocking it and that it's far enough away). Building these below your swimming ability allows for easy access to late game resources. HUD scanner chip is worth it (goes on your stuff like armor), cameras are not.
I never needed torpedoes, seems like a waste of resources.
I never needed a land base, didn't even try. But do carry a flare and several beacons when you hit the biggest land section.
Don't use the numpad to launch the land vehicle, always right click to drop it straight out of inventory to avoid clipping glitches.
