While the Roomba 677 still cleans very efficiently, there are issues with finding it and even docking with the charging station. I have been using Roomba for 10 years and have 3 units for different households, model 677 is the newest. There were no problems with the previous ones (except replacing the battery with the oldest, which is normal). 677 often gives error 19 and error 6. The model sold in Latin America does not have a built-in Wi-Fi module, so do not install the application. Finally, it has the smallest dust bin, so it might not be suitable for large or dirty rooms.