Wow, the narrow mindedness of some of the posters in here is pathetic...
I've driven an '09, '10 IS-F, and am looking forward to driving the '11 model; I've also driven my fair share of M3s as well, both e46 and e92.
I believe the e92 M3 is a superb vehicle, it's the culmination of 3, prior, generations of evolution and refinement.
That said: It's clear that Lexus has listened to its customers, critics as well, and has created a product that meets, if not exceeds, the same standards as the M3.
I'll be in the market for a new car next year and I can assure you I'll be considering the IS-F, M3 as well... if it'll be around for a '12 MY.
What can't be denied, marginalized, etc. is the fact that the IS-F, within its first generation, has managed to meet the performance figures of the sport's car "standard" that is now on its fourth generation; I, subjectively, find that pretty damn impressive.
I'm no more a fan of Lexus than I am of BMW, but I believe credit, when due, should be given.