So, I have about 4 hours into Dishonored: Death of the Outsider so far. Some thoughts incoming.
It's basically more Dishonored 2 with some twists. I'm right now (still) on the second level. Yes, I've spent a decent about of time in each level, so far. Good amount of lore (written books, letters, etc) and there's some audio-logs here & there too. There's some side quests here and there, in which you have to either assassinate someone or do something (steal something, kill someone, or whatever they ask of you) in often a certain way - which is probably one of many reasons this game dropped the Chaos System.
Since I'm on that topic, the Chaos System is gone here, probably since story-wise both Billie and Daud are pretty much on a revenge path here. It's not really about stealth here, it's about revenge. You really should know your Dishonored lore here, having played everything so far in this one - i.e. Dishonored 1 (base-game) & its two main DLC's (The Knife of Dunwall & The Brigmore Witches) and Dishonored 2. Otherwise, you might not get the references here and there...and you might get lost here. It seems like this, so far, is trying to fill in some of the blanks and stuff that was leftover from the last few games, which feels like it's playing (fan) service directly to their fans.
Since the Chaos System's gone: you can go non-lethal stealth if you like, but you won't get penalized by the game if you do go full blown lethal on anything and/or everyone. The Chaos System usually was there for getting better endings, if you play non-lethal - which seems completely gone. Even in Tutorials showing you how to play the game, they do emphasize on lethal and non-lethal play: do what you like. You still get scored & gain stats like Dishonored 1 & 2, though...in case you are challenging yourself here or trying to top others. There might be Achievement and things just for going non-lethal and not killing anyone, if you go the non-lethal route.
Billie's version of Blink - which is called Displace, by the way - actually displaces an image of her to a location before she teleports, which you can use to set enemies up and get them chasing either the real Billie or the image of Billie (depending on who they see) - and you can command when to then make the switch between the two. Another skill lets Billie ghost around the area for a short time and see the lay of the land like an X-Ray mode, where you can mark items and enemies, and whatnot so you can take care of business. Also, Billie can steal now another person's face and walk around with their face to try to get into certain special locations, do special events, and whatnot. This skills are an absolute blast to use, as you'd expect with the typical cool skill sets you often see in Dishonored games. Oh, and Billie can understand rats and talk to them, to try to get information and hints about...well, who knows what.
Basically, this is more Dishonored 2. If you liked or loved the Dishonored series, you'll probably like this too. So far, I'm really liking this.