For me, not talking about commerce here, but moreso just personal expression,........snip.................
* Ability to successfully flare in backlight: ______
for me, the one ground breaking camera, film or digital was the original 1ds.
It opened a new world as it looked like film, rarely moired, never broke and though by today's standards it was slow and had a tiny lcd, it allowed me to do more than I've ever been able to do, especially in commerce because it let me get the base idea in the can, know it's right and get on with experimenting.
I told our studio manager then and I believe it today that I should have bought 6 of those cameras, put 4 in a safety deposit box and never buy another camera. I would have saved myself $120,000 and about a billion hours or learning curve.
In fact I use to laugh at how easy the 1ds was for first level post production. I had the camera zoned out for the look I wanted, I'd just take the in camera jpegs and drop them into a web gallery and usually upload at a restaurant, coffee house or hotel patio while I enjoyed life, but being a masochist photographer I wanted more and dived deep into everything, including processing out jpegs until 3am.
I think it's easy to be nostalgic over film and some things I miss, like talking to the photographers at the labs, but some of the things I really don't miss, like seeing snips pulled 2/3's of a stop rather than pushed.
The only thing I really miss about film is the ability to shoot into the sun and get that soft pretty flare around a subject. Now that's something that almost always has to be modified in post production. I miss that and like gwtif says the happy little surprises, but not the unhappy big surprises.
Now I think I've come full circle in the digital world shoot 90% of my still images with the 1ds3's and the only camera that would make me open my wallet is this.http://www.dpreview.com/reviews/PanasonicGF1/
though I haven't bought it yet, or used it yet, but it looks intriguing, with multiple crops, 12 film settings, takes almost any lens and shoots video.
Actually maybe not (here I go again), as I did love the Aptus 22 with that Boris tilt shift. I didn't like the issues of the early Aptus (in all fairness Leaf eventually worked most of those out), but the look of the file was really nice with that funky lens.