I hated the Tektro brakes that came with my bike with a passion, about a month ago the rear brake failed completely just about when a SUV made a right turn in front of me. I had to make a closed turn along with the driver, thankfully he wasn't rude, or I would have ended squashed. I was literally just two blocks away from an area with bike shops, had them upgraded to Shimano right then.

The disc on the back wheel had been squealing badly, just yesterday I went to the shop near home to have that checked, it was Sunday so the place was packed, but the mechanic still spent a GOOD amount of time checking it out. Unfortunately a guy at the counter said something before like 'you're scratching the disc you have to change the break pads right away'.. Well it wasn't the pads, the disc was crooked, and it took the mechanic a long time to straighten it up properly.
I still ended up buying break pads I didn't really need

Not sure if the disc became that way from some bump, or if it happened just out of 'normal' wear.