About 90 minutes in, some initial impressions for those that might be on the fence.
The disguises do slow down the game a lot. Not being able to run, jump, and climb makes the game less enjoyable.
Also there are a ton of graphical issues, from MPCs popping in 3 feet in front of you, scripting issues with enemies constantly running into walls, awkward combat, etc. As others have mentioned, the framrate hangs out in the low 20s, not game breaking, but annoying.
And as I mentioned before, the audio is pretty terrible, like N64 game muffled voices and music. Going to try Uncharted and NFS: MW tonight. Hopefully those fare better.