Finished it yesterday.
Very short, but good, not great.
Bloober Team really tried hard to create their own SOMA, and Observer is what we got.
The entire searchlight stalker stealth sequence is basically ripped off from SOMA, and SOMA's shambling turd golem is much more effective.
The puzzles are all very simple, off the top of my head, they were mostly plugging in electrical sockets, hacking door codes, hacking computer passwords, and one instance of guessing a combo lock.
Unlike Frictional Games, Observer's world is a lot less interactive, which is another fault, at least for me.
Besides the very talented Rutger Hauer, the rest of the voice acting and dialogue is pretty bad IMO.
Certain areas, overcrowded with pigeons, could have been a lot more subtle and not attempt to knock players out with the obvious Blade Runner reference.
The best parts of the game were very frequent: scanning crime scenes for organic and digital evidence, hearing Rutger Hauer's growing desperation through his excellent voice acting, and hacking into NPC mindchips.
That last part is also simultaneously the least interactive part of the game, and not all the mind hacking sequences were good, some were decent, and others were dull and boring.
Based on my experience with Observer, it's Bloober Team's most well reviewed game, so I'm not interested in Layers of Fear or The Medium, because Observer is about 3.5/5 stars for me.