You get what you pay for with controllers. It's all about how the controller adjusts and ramps up the brakes in conjunction with the truck's brakes.
The cheapest controllers are like the one I use, they ramp up the brakes on a time delay basis only. The longer the controller sees voltage from the truck's brake switch, the more voltage it applies to the trailer brakes. This is better than nothing, but has some drawbacks. The obvious one is during a panic stop when you slam on the truck's brakes, the controller is still doing it's ramp up thing with the trailer brakes, and by the time it's done you have already run over what you were trying to avoid. The other one is when you are lightly riding the truck's brakes, the controller doesn't know this, it ramps up as usual and the trailer brakes start coming on strong when you don't need them. This is easily remedied though, by just letting up on the truck's brakes and then re-applying them. This starts the ramp-up cycle over again till the trailer brakes grab too hard again.
They have more expensive ones with pendulums inside that swing and try to read what you are doing with the truck, and there are really fancy ones that do this electronically. You can spend as much as you want, the more money you spend, the better they work.