Dishonored takes a very accessible approach to stealth, the player quickly gets access to very strong magical abilities, resources are abundant, the story is fast and easy to follow, and the only things that matter for remaining hidden are line of sight and sound. Not to mention the player can't be spotted for leaning. The game is also very polished when it comes to presentation, performance, attention to detail, etc.
There are also lethal and non-lethal tools and the game reacts to the player accordingly which is way better than reducing moral choices to dialogue options and button prompts like so many games where "choices matter" do.
There's really not much else to say, Dishonored is good. I believe it's maybe a little too safe design-wise, but I literally can't think of anything else to criticize about it.