It’s a little late coming, but Road & Track’s review of the Lexus IS-F is quite informative. First off, their impressions:
After spending half a day lapping around Laguna Seca, we were won over by the car’s accurate steering, minimal body roll and outright grip. Its 71.2-mph slalom speed is damn impressive for such a heavy sedan (3825 lb.), eclipsing not only the Audi RS 4 (68.9 mph) but also the Porsche Cayman S (70.6 mph). The 911 Carrera 4S barely edges the Lexus, at 71.5 mph.
Where the IS F struggles is on overly bumpy back roads; in that setting, the suspension’s lack of compliance makes the car flit, flutter and skate across the road like Helio Castroneves on Dancing with the Stars. But on most roads, no such problem.
The most impressive part of the review comes in the form of a full technical breakdown spec sheet, which you can view here (in PDF format). This includes some extensive data, including gear ratios and even the interior noise levels. Very interesting.
Bonus: Be sure to check out the video of Scott Pruett lapping the Laguna Seca Raceway.