Excellent!
I've been using this TDK BD-RE 50GB disk for six months now. Its been erased and rewritten eight times and still going strong.
I purchased it along with two Verbatim BD-RE 25GBs, and two TDK BD-RE 25GBs, all of which are at an astounding twenty one erases and rewrites each.
Very impressive perfomance for all so far! Far better than I had even hoped for.

Worked for 5 rewrites
Did 5x (full erase, image burn). Worked on a PS3 Slim but died after the fifth burn.

This may be better than can be expected for a 50 GB rewritable though.

Flawless 50Gb recording for dual layer
I've burned, erased and re-recorded on two of these pricey 50Gb BD-RE media I purchased from Amazon. Every dual-layer burn has been perfect. Prices will come down over time like SD DVD did. I'm amazed in that I have an old dual layer SD DVD burner (~8Gb) yet the industry never produced a dual layer rewritable SD (~8Gb) DVD medium, only single layer (4.7+ Gb) re-writables have been available. Now years later, Blu-Ray offers this ability on a DVD that's over 6X the older format capacity. 'bout time! For consideration to those shopping for a PC/Mac Blu-Ray drive offering read and WRITE capability, I have the Buffalo Mediastation Blu-ray/DVD/cd Combo USB 2.0 sold by Amazon (I got mine on sale at Circuit City for ~0, although I would expect Amazon to come down on their price for this since typically they are always very competitive on almost all of their pricing - Burning and playing software is included with the drive). I use a Mac but with Windows on Boot
Camp. Works like a charm! (yes, you can burn on a Mac and it will support the drive. but, for most burning and anchoring and most importantly, -playing-, Windows still leads the pack for Blu-Ray support.... come on Apple!)

Best in class right now!
Does exaclty what it is intended for, re-records, and holds 50GB. It is also the cheapest I found, so it gets 5 stars. as the other reviewer stated, hopefully the price of these things will drop soon.

So much memory!
I have a Blu Ray burner on my Sony Vaio VGC-LT28E computer and selected this TDK double layer RE-recordable disc because it holds 50GB of information but also for the fact that it is re-recordable. I've been storing a great deal of high definition video, which takes ALOT of room. Consider that a standard recordable DVD holds just 4.7GB.

You can find far less expensive recordable Blu Ray discs, but so far, these are the state of the art! Prices will hopefully drop soon. That's been the case with all this sort of stuff.