Um, I have to say I am kind of surprised here. I just assumed that both "formats" were basically the same, with different storage, HD-DVD being worse off, but, uh, woah.
Hot Fuzz on HD-DVD is quite a bit of a better package than ANY Blu Ray I have seen.
Right out of the way, image quality is about on par with Blu-Ray. My PS3 is HDMI, my HD-DVD is component, so there is a slight quality hit there, but that would be corrected if I had an HDMI 360, which will happen soon.
But aside from that, HD-DVD is pretty clearly the winner in basically every other category. It's got much nicer menus, and a FUCKTON more special features (over ~18 categories of special features, just under 40 total, severl of them of considerable length). The menus are impressive all around. When you press the menu button, they pop up 360 dashboard style, rather than going to a DVDish menu, which is how I've seen it done on every BD so far. The UI is also pretty good. I can't really hold that against the BD format, but more of Sony's piss poor design of the PS3 DVD/BD interface.
So it's in the details here, but HD-DVD has kinda surprised me. I thought people were exaggerating the special features difference, but my mind is blown here.