I have a few and love them. They stick wonderfully; I haven't had any loose their stickyness. They clean with regular stamp cleaner, but can also be cleaned with soap and water.
If you stamp in black, they will take on a little tint, but I haven't had it interfere with my stamping in any way.
Also, I would not do bleach stamping with acrlyics, but I also know that there are different ways of making them and the lower end ones should not do bleach, CTMH may be fine to do, but I prefer not to chance it.
Unmounted is certainly an aquired taste
But I absolutely love it. Acrylic makes it easier.