This disposal is obviously better than the one I'm replacing (lasted 22 years!). It is much quieter, and seems to do the grinding quicker. The plumbing hookups were slightly off, but for the most part could hook up with the old connections. The worst part was final assembly of the unit with the sink hookup. At first, could not get the snap ring around the flange. Had difficulty holding the flange in place which expanding the snap ring at the same time. Eventually rigged it up by placing a small item between the ends of the ring to keep it open while installing. Just as difficult was step 22) aligning 3 mounting tabs with slide-up ramps on mounting ring. Not having an assistant to help me, the unit was becoming heavy, and had to be precisely aligned to hook on. Eventually I got lucky and hooked it on. Overall, the snap ring and unit mounting took me over 1 frustrating hour to perform.