Speaking from first hand experience I can tell you the Rx300 is a great vehicle.
The first year production is in fact 1999.
The only things I can see being a common glitch on first year production vehicles is the rear tailgate shocks (slow opening), and the front struts in cold temperatures seam to bottom out.
These two items I know for a fact were dealt with in the '00 and newer production run...
One other item, do some research on the size of the fuel tank on the earlier rx300 it is surprisingly small, infact, they enlarged it in 2001 (I believe) due to customer complaints. The small tank (65 litres)combined with fuel reserve light coming on too early (12-15 litres left in tank) results in relatively short distance on full tank (my case 380km until reserve lights on).
-Oh, another thing, poor turning ratio.
Other than the above (minor issues) its a solid, reliable and well built vehicle.
Toyota relies on previous reliabilty history of their vehicles to develope their product line, which results in better vehicle every year....
I am not a fan of first year production vehicles yet, purchased a '99 rx300 go figure.... No regrets, and yes I would do it all over again.
Cheers,
Fern