The smaller track pitch (740nm vs 1600nm) and pit length (400-440nm vs 830nm) for DVDs mean that for the same size, media defects/damage would affect a much greater area relative to a CD. I heard that the error correction redundancy in DVDs is more streamlined than CDs, but I do not know if it takes into account the greater damage sensitivity of DVDs over CDs. Any info?
Same as in pressed DVDs, they’re much more susceptible to scratches, but they don’t degrade faster with time. (At least not in acc. aging tests.)
The only problem is that since DVD is relatively new, the manufacturing processes are not as refined as the CD-ones, and the crap media tends to be really crappy.