When I played it a few years ago seemed to be 1600-1700ish USCF at level 10. Didn't play it too often because it took so long to move heh.
And like most computer opponents, it was much better in open games. If you built up an attack in a closed position, it pretty much ignored the danger, and you could pull off some very simple mate attacks. So the rating would vary. When it ignores these attacks my estimate would be significantly lower.
I would like a rating for chess titians