Now that I've finally outed my unquenchable thirst for that old-school, all-rigid mountain bike aesthetic of the late 80s/early 90s, I can't help but pick it apart. It's the curse of having been to graduate school in a liberal arts field: You can't just "like" or "dislike" something, you have to analyze (in stomach-churning detail) exactly WHY you "like" or "dislike" that thing.
For retro mountain bikes, I think it's the way that their underlying shape never seems dated (I know, talking about "underlying shape" ignores the twin elephants in the room of hideous 80s paint jobs and 90s anodizing. My blog, my dodge.) Take, for example, this Bruce Gordon Rock 'n' Road Tour EX. Admittedly, it's not really a mountain bike per se, but it's an example of a 26"-wheeled all-rigid bike you can buy in 2009. You don't have to squint much to see the direct lineage back to the brief era of late-80s drop-bar mountain bikes like the '87 Bridgestone MB-1 or the '89 Specialized RockCombo. And even though the Gordon in the photo is probably 10 years old by now (just judging by the vintage of its XT parts), it wouldn't look out of place up against today's Surly Long Haul Trucker (which owes a lot of its genetic code to Bruce Gordon's designs), save for the whole threaded/threadless steerer difference. Similarly, you could fire up the flux capacitor and send an '09 Novara Buzz V back to 1993 without freaking out the trail riders of 16 years ago with your crazy future bike. Heck, they'd probably call you retro for not having a suspension fork!
My more-purist pals on the iBOB list will claim the same sort of timelessness for a lugged road frame, but my eye doesn't see it. I really like the '71 Raleigh International I got from pal Steve, but it obviously comes from another era. Modern "frilly lug" designs (like those from Rivendell) strike me not as proof of the "timelessness" of that aesthetic but as desperate attempts to get back something that's long gone. And modern "Raleigh" (scare-quotes intentional) -- with its retro logos, 70s color palette, and sprinkling of Brooks leather eye-candy -- looks like a room full of marketers trying to add scratch-and-sniff "authenticity" to yet another lineup of generic imports.
I'm also willing to admit that maybe these preferences are just because I bought into the "rad, cool, extreme" marketing when I was an impressionable youth and never gave it up. Hey, my sacred cows tip over just like anyone else's!