Using my (Sony) DVD writer drive, I've been attempting to burn backup DVDs using these disks. Out of the 30 disks tried so far, 18 have completely failed to burn. 20 remain on the spindle, and I'm not very tempted to continue trying to use them.
Burning was tried at 4x (the speed of the drive) and, in some cases, I knocked the speed setting down to 2x, so it's not a speed issue. And it's not a problem with the drive itself either, since burning other brands of DVDs, including cheap "WorthIt" ones from Woolworth's which I've just bought to complete this backing up process, works absolutely fine.
These are possibly the worst DVD-Rs I've come across: A 60% failure rate is absolutely unacceptable - and I'd advise anybody to steer clear.