Mine arrived yesterday morning
It's pretty awesome so far, though I'm not *that* far in yet. The blurb comparing it to a mix of Half-Life 2, Thief and Bioshock is all pretty accurate - definitely getting that vibe so far from it! Combat isn't too bad, and the stealth has felt quite Thiefy/Deus Exy (in a good way). So.. yea, I like it.
Bethesda published it, Arkane developed it, and it's using Unreal Engine 3, not the Gamebryo stuff. Admittedly, if they were using Bethesda's QA there's probably something that'll go wrong soon, but my xbox version has been fine so far
(not that I've actually had any big issues with any Bethesda games)