I test drove the IS-F at California Speedway track in Fontana, California...
The IS-F looks great on paper and it drives pretty good. I don't like it because of the styling, lack of wide body that the M3 has and the biggest reason - lack of manual transmission. I think the regular IS looks way better than the ISF.
If they had one that had better styling and a manual transmission, I'd seriously look into purchasing one. Lexus interior and overall reliability is great.