Super easy to install!  We needed the top-mount kit in order to work with our hidden-side commode.  Even with that added step, installation still took less than a half hour and only a screwdriver.  That reflects solid engineering.
The seat is sturdy and comfortable.  The lid is sturdy enough to sit on.
All of the features work as expected.  My wife and I are both very satisfied.
The control arm is very close to the seat.  If I had it to do over again, I would probably opt for the SE600 which has a remote control.