This was a quick and easy swap-out for a Shimano Altus derailleur originally on a decade-old Cannondale H400. The old derailleur worked well but the shifts were just a bit sloppy under load. For $11 + S/H, I popped off the old derailleur, popped on the new, routed the cable, adjusted the stops, and hit the trail. Perfect - no noise, smooth ride, snappy shifts, easy installation, cheap as heck. Buy it with confidence.
Update: Three months later and I have had zero issues with this derailleur. It is as fast, clean, and quiet as on Day One.