I did a lot of research before I bought my CPO Lexus (2000 Lexus ES 300 Platinum Series). The following links offer reviews and opinions from actual owners and professional reviews.
http://www.edmunds.com
http://www.epinions.com
http://www.carreivew.com
http://autos.msn.com/
When you get to the sites, just search for the Lexus model you are inerested in.