I've had my IS F since 2/18/08 and have nearly 6k miles on it. I can honestly say this car is about as perfect as I could ask for, both in terms of daily driver comfort/amenities and in terms of becoming the "beast" I paid so much for when I step on it hard.
I very nearly bought the Mercedes CLK 63 AMG Black with 507 HP and incredible torque, but upon reading about all the serious reliability problems Mercedes has been having, the decision to buy the F (and save probably $50k!!!) was a no brainer.
Test drive the car, for sure, but once you do, be warned--you may not want to even consider anything else.
Oh, and be absolutely sure you put the car in "Sport" mode with paddles working before your test drive is done--unbelievable!
Hope you get one...this thing is amazing.