Well I haven't seen anyone review the GS 460 for '08 (I may have missed it) so here you go. I am not what you would call a real auto enthusiast.
My previous car was a 740iL so I may do some comparison which may or may not be fair.
Clearly the body, styling and interior of the car are the same as other models so I won't bore you with complaining about the navigation system while moving or whether I like the wood etc.
The new aspects of the car, so far as I can see, are the 8-speed automatic and the V-8 in this class.
Although the car has similar horsepower to my 740, the performance is not close to the BMW. The 740 could lay rubber from the start or by punching it at 50MPH. The 460 can pretty much do neither (of course it can spin the wheels if you hammer it off the line, but the 460 needs to make some noise and think about it awhile first - the BMW just... responds instantly). I was really expecting a car that could get you out of any freeway conundrum - like getting you away from being surrounded by big rigs in seconds flat - but the car really hesitates and again - seems to think about it - before doing exactly as instructed. I have much less confidence in the overall performance than I was used to with the beemer. The untrained 740 driver will throw passengers around the car with the instant handling - the 460 just mushes its way through.
The 8-speed automatic tranny. As a layperson re: transmissions, I was expecting an 8-speeder to roll through the gears with buttery ease. However, after only 3,000 miles I find myself counting all 8 gears as the car accelerates - bumping my way through each shift change with increasing annoyance. First gear seems to take forever, and decelerating slightly before 2nd will give you a kickback that shoves you forward in the seat. This is especially apparent when cold.
The car is smooth at higher speeds and a comfortable ride on an open freeway. So was the Chevy Cavalier I rented recently while out of town.
Just touching on the amenities, I am enjoying the ventilated seats and the overall control system. The voice activation is just OK and forgetting about the restrictions while moving, the nav system is nice - took awhile to learn it and I still am learning it. I was spoiled by the 740iL rear seat room but this is not a fair comparison - neither is the trunk (very small in this Lexus).
In summary, I needed a quality, comfortable commuting car to hump the LA freeways - my Beemer at 7yrs old was killing me with operating expenses - and the second tow that caused me to miss a meeting was the last straw. So, the real test of Lexus (my first) will be in the reliability. If it is better than BMW, I will have got my money's worth (BTW I paid $54,500 fully loaded with a $15K trade in on the 740 with 90Kmi and a couple of dings).
Ok, hope there was something helpful in there.