Even at the correct IS pricing, it shows the BMW 325i is VERY competitive in it's segment. The base 325i without any packages is a very well equipped car, has a superb I-6 engine, terrific manual trans, and is a very well-thought-out package. At $40K flat, it's tough to beat.
The G35 is getting a little long in the tooth, but will appeal to those in need of HP numbers. I think the new interior is better, but still lagging behind the Lexus and the BMW.
The real buy in the Lexus IS series will be a base IS250. In four years, all the IS250's off lease will be priced about the same, so a base model will hold it's value better. The lower initial upfront investment is nice, too. You get all the "Lexus goodness" and save some bucks. The base IS250 would be the "buy and keep" car. If I were leasing and had no intention of buying the car, I'd option it up a bit as the increase in lease payment would be marginal.
I don't get the IS350, C350 and other "high end entry level" models. Personally, instead of a $60-$70K C-Class (as many C350's are) I'd get a 5-series BMW. No fuel economy penalty and a nicer car overall. A $58,600 525i is a pretty SWEET car.