I nearly had a panic attack when I saw there was DLC for Outer Wilds, and bought it instantly.
EOTE is extremely clever, just like the main game, and the way they have integrated it is gorgeous.
It's aesthetic is magnificent, and the way the mystery unfolds is worthy of the root game. There is some truly haunting stuff in there, and some tricky and clever mechanisms.
But it's just too hard. Once you penetrate sufficient layers deep to figure out what's going on, and get a grip on the mechanics, the time and other limits start to become very, very tedious.
I ended up watching an 'official' walkthrough just to see what happens, and while I was pleased at how far I'd made it on my own, I was amazed by the tiny clues and convoluted paths one was expected to follow to solve the whole thing. EOTE is much harder than the root game, but ... not in a really enjoyable way. Also, combined with the horror dynamics that have been introduced, it goes from sweetly wonderful to bitterly off-putting rather quickly.
But would I recommend it?
Yes of course, but if you're a fan of the stunning, astounding original game you're already aware of EOTE, you don't need me. This review is largely for Annapurna to read. They reached too far, but in the wrong direction, I feel.
Buy it, check it out, but be prepared that unless you have limitless time you are probably going to give up on it at some point, even if you doggedly made it through all of Outer Wilds by yourself.