I bought my first Chalklets several years ago and have added many more since (I have 9 color sets). I use them for scrapbooking, cardmaking, and to enhance diecuts. I have had no problems with any of them not holding up. I would highly recommend them to anyone who enjoys the soft look that chalk gives.
I tried chalklets and found them to be very cheap in price, but also cheap in quality. They were so soft and crumbly that the blocks fractured just from rubbing a cotton bud on them,(and when I picked one up to try and chalk directly on the cardstock, as suggested by the directions, it broke into pieces immediately) and the chalk colours in my set were EXTREMELY pale and didn't even show up on the paper. Lastly, the colour on the outside of the chalklets did not match the colour on the inside of the blocks once they were broken open. Inside was much paler. Never again.
SINCE I'VE STARTED MAKING MY OWN CARDS FOR THE HOLIDAYS, THIS IS THE BEST.