I had it before... It's good for running Atari BASIC programs but way too slow for games. I used it to make some cool screens that I then put in DEGAS using a screen cap program.
I haven't found a game that's playable yet, so yeah, no quite what I was hoping. I did manage to convert a few ATR disk images to XFD format, but they'd start to boot and I'd get an initial loading screen, but then it appeared to hang or was just running so slow I didn't get anywhere. Oh well, worth a try. Maybe time to buy a real 800XL