See Issues for a list of the main issues with the PC version of Dishonored 2.
This non-official list of issues is compiled by me, an owner of the game, and is not endorsed by Arkane Studios SASU or Bethesda Softworks LLC.
The intention of this GitHub repo is to provide Arkane Studios with a simple and concise list of the most important widely-confirmed issues separate from lots of comments and discussion (which are not always constructive), and to ensure that less immediately noticeable (but important nonetheless) issues, such as mouse acceleration, are not missed. It may also act as a useful reference for owners of the game or those thinking of purchasing the game. Issues will, of course, be closed once they're fixed.
As an aside, it's a shame that such seemingly obvious issues are present at launch (I wish developers would get experienced PC gamers to give feedback on things such as mouse control), but it's been encouraging to hear that Arkane is listening and working on fixes. Those who get playable performance and have played Dishonored 2 through seem to rate the game itself very highly, and I'm looking forward to experiencing it once the major issues have been addressed.