I thought i'd just jump in here as there is a lot of BMW and M3 bashing... and once upon a time i would have joined in...
except, BMW make fantastic cars - the M3 is a simply stunning piece of engineering, yes the older ones have a few known problems (such as VANOS), but most cars do (911's have RMS issues).
When i was shopping for a car this year, i tried a hell of a lot of serious machinery, and BMW kept delivering where others failed - take the RS4, i wanted one so badly, and was prepared to part with nearly £30k to have one, except it was very dull to drive, and while fast, it never felt so. Whereas a E46 M3 CS at half the price was a lot more fun and certainly felt faster...
I havent tried an IS-F, and would love to, but I somehow dont think it would compare to the latest M3 in terms of driving dynamics, not because its a bad car, but its something BMW just seem to have nailed... which is why i bought one!