*****Sharks will not attack you******
Now that's that out of the way. I pre-ordered this from their website so my play time has been almost entirely outside of steam. Would I reccommend this? Yes. It's a work of passion that deserves the following it needs to bring to all of its ideas to life. That being said I would like to offer a word of caution only so that people know that they're buying into now and don't potentially complain in the reviews.
In it's current state there isn't much to do beyond dive in the available areas and simply explore. Each area has a wreck that you can swim around (or inside) and each map is reasonable big, but that's about it. There is a daily mini game you can play where you have to find an object within a time limit, but the game basically tells you where it is so it will last 2 minutes max. You can clip directly through fish and plants, and you can't manually change your orientation. So no swimming upside down.
There are microtransactions, but they're purely cosmetic and don't at all lock off any meaningful content.
To sum it up: In its current state it's more a virtual museum than anything.
That aside the game looks great. It has full controller support and the multiplayer works really well. I personally find it both thrilling and tense to swim around the detailed enviroments and you can even tread on the surface. You can also take pictures of anything you like and save them to your hardrive.
This is a very cool game and a work of love, but very much Early Access. Given time I have no doubt it will be amazing!
P.S. Rift Supprt