They are not junk. Are you saying that based on your own experience, or was it something you heard?
I have a few of them, and have never had issue. they are a bit of a pain to set up because they don't have a digital temp display... so you have to use with a digital thermometer or heat gun to get them set.
But once they are set, they are good to go. They keep my temps within 1 degree. And never need further adjustment.
Obviously they are not a helix or herpstat.... they are not proportional (meaning they turn the eat source on and off, not adjust the power) but they also don't cost over a hundred bucks!
Reptile basics sell them for 20 bucks, but you can't get them at a local pet shop usually for less then $35.
If you look hard enough you will find a horror story for every single thermostat out there. That is why you should use a backup thermostat when you can... two 500 R's can do that for $40. One to do the normal work, and one set for 5 degrees higher "just in case"