Some are better than others. I bought two pads; a TX1000 and a TX2000 . Both pads had broken controller boxes and I had to repair one and had replaced the other. The pads themselves feel great, and I have been stomping on them for 2-3 years with no cracking or contactor failures. I weigh about 160 pounds. Also, they don't shift around like the soft pads.
Here is a good source of personal reviews and other info on specific pads. I heard cobalt flux is the best retail pad going:
drfreak