I've had these cups, and the rest of the matching set, for over five years now. The enamel survived life in four states - and part of that trip was getting flown into and out of the Alaskan bush. It wasn't until my husband accidentally knocked the stack from the cabinet that any of the enamel chipped. I'm actually quite impressed, which is why I will be coming back to this site on payday to replace them.
When you're using them, I do recommend getting a matching saucer as well. The cups get quite hot. I use the leaf pattern with mine, and not only does it look nice, but it saves both your hand and your table from the heat!