Great stealth game overall. I played it mainly for the gameplay, and I had a good time. Mechanics are well-implemented, stealth movement and kills feel great, objectives can be completed in multiple ways, they are not streamlined from A to B. There are only 5 main quests, so the game can be quite short if you only focus on the main objectives, however, there are a few side mini-quests, and exploring your surroundings is quite nice, as the world is pretty nicely built and very detailed. Graphics, although a bit dated, still look really good. As far as the story goes, I can't say much about it, since it's pretty tightly related to the other games, and I have not played through them yet, unfortunately. If you are a fan of the previous games, I'm pretty certain you'll be satisfied with it. There are many written pages, stories and journals as well if you want to dive deeper into the city environment and people's stories.
As someone who went into this game strictly for the stealth gameplay, having known nothing at all about the story, I was left satisfied with it and I want to eventually play the first games as well.