I did a ghost playthrough of Dishonored and it's fairly easy as far as stealth goes, but it's not bad. The blink alone makes traversal rather trivial and further reveals how daft the guards are, but I don't remember them being much smarter in any Thief game. If you turned the UI cues off and abstained from using blink it would play very much the same, if perhaps a little more frustrating since there's no hide in shadows mechanic or UI to tell you how well you're hidden. But there are a lot of places in every level that you can rely on being safe hiding places, so it might even out.