I use these markers just about everyday at work and at home to label the CDs/DVDs that I've created.
The ultra-fine tip is perfect for writing a large amount of information in a small amount of space, and the ink dries quick enough that your writing is smudge-proof in a matter of seconds. There is a slight "marker-type" odor when remove the cap, but it is not too bad. The label states that the ink is non-toxic too, but I've never had the urge to test that claim out. I'll just take their word for it.
When properly capped after each use, I've had some of these markers last me for years. You've heard the phrase "nothing lasts forever", though, right? Permanent ink is no exception. Over time you may find that your writing will begin to fade slightly, and I have found that with the use of some rubbing alcohol and a little effort, I was actually able to completely remove the "permanent" ink from various surfaces.
If I had to guess, I'd say that nearly 95% of all of the discs I've ever burnt have been labeled with one of these markers, and I'll gladly continue to use them for the foreseeable future.