One thing to add: I discovered that DX:HR is playable - sort of - even on single-core Athlon XP systems with AGP graphics.
I played through the opening gunfights to the beginning of the first sneak-in mission and didn't encounter crashes or agonizing level load times, even with the unpatched game (some minor problems with sound, though). The benefits of development starting in 2007.
I can't say I liked the way the game force-fed me the basic storyline. You naively click on the lady by the door and get dragged along on a minute-long, involuntary sight-seeing tour where all your controls - except for looking around - don't work. Not especially thrilling. The original Deus Ex thrust you right into a situation, with skippable conversations from the get-go if you didn't particularly care for the specifics.
Are some games inherently more fun than others? - definitely yes.
These first impressions of HR were gathered a month or so ago. I'll go on playing as time permits & interest resurges.
