I recently bought some of these to copy some old tapes using a Pioneer CD recorder standalone unit. Since I've got a load of tapes to get through it made more sense to go for re-writeable discs as I can just record on to them, extract the audio off on to my PC for editing and then blank the disc and re-use.
They work fine but I actually started keeping a rough tally of how many times I'd used them as some TDK ones I'd bought previously had all seemed to "die" relatively quickly. I was a bit disappointed when the first one brought up the dreaded "CHECK DISC" error message on the Pioneer after about 8 or 9 uses. I put it down to bad luck but was soon to find that the second disc only lasted a little longer, managing to re-write about 20 times before it too went to blank media heaven.
Now, I'd like to think I'm not especially gullible and I didn't seriously expect to get anything like the 1,000 re-writes that is quoted (or even a tenth of that) but to barely get 2% of that figure is pretty poor. The discs were kept clean and either in their cases or in the CD recorder at all times so I can't even put it down to dirt, finger prints or scratches etc.
In conclusion: For what you're paying then ok, you save a little over buying CD-Rs which you can only write to once. 20 burns for a quid certainly isn't bad and maybe I'm expecting far too much for my money but I do think that if manufacturers are going to quote figures then the product ought to at least bear some relation to them in reality. Even if you were to take 100 re-writes as a more realistic figure then 20 is still not good enough. I've got VHS tapes from the 1980s which still re-record fine so I was expecting a little more durability from digital media. Oh well, they don't make 'em like they used to, eh? :)