I ended up putting OS X 10.3.9 on this which is the latest it supports. It isn't too bad with the RAM maxed out at 512 MB. Not as snappy as OS 9 but you can run more modern software. Just don't try web browsing...
I remember seeing these when they first came out at Comp USA. They were really the first computers to do away with the floppy drive. They were pretty neat computers but by this point I preferred building my own which you just can't do with macs and while these were cheap for macs they were still overpriced for the horsepower you got. Not much has changed in that regard...