My Roomba 530 from 2008(?) still goes strong, even if it looks like a war victim after bumping into too many objects. I've replaced the battery with a nonstandard lithium-ion, did a regrease, and replaced the bristles a few times. It always worked good enough for a midweek cat hair cleaning cycle but could never replace the full vacuum.

We were looking to replace the poor thing in 2017 or so, and found iRobot wanted WiFi connection to upload our floor plans to the cloud. No way, was our reaction, so we bought some aftermarket parts and revived it. I do wonder how well its scratched surface still detects walls.