I used them on all four corners on my wife's '02 Corolla, a pretty lightweight, simple car. The rears were fine but the fronts were under-dampened and under-sprung. They felt like they were worn out right out of the box. The top mounts were a bit cheesy and they started getting noisy after about a year. The top nuts would loosen up easily on both and the bearing failed on one of them, which was replaced with a like-OEM KYB part.
That said, Toyota lists something like five different coil springs for the front of the Corolla depending on what transmission and if it has A/C. Monroe chose one spring rate that worked 'well enough' for all of them, but it was too light for her 4-speed auto trans and A/C car. And regardless of the too-light spring rate, the dampening rate was too soft also. But again, the rears were fine, and that's probably because the OEMs were the same across the board regardless of what was on the front.
Cliff's notes: Your experience may vary but the quality just didn't seem to be there.