We are Roomba early-adopter. We bought the 1st version of Roomba. Although it’s cool, the 1st Roomba had many shortcomings. iRobot later released Roomba Discovery 4xxx with auto docking features and a lot of improvements… Later, we upgraded it to Scheduler.
Now, we got Roomba 550 from Costco. Again, it has many improvements over the 4xxx series. It doesn’t get stuck easily but it still gets stuck. It ate my cellphone charger cable; it stopped at black strips on my carpet (confused sensor!).