I guess that since you are not driving a 2010 model (your profile says RX300) you're not really able to make an informed comparison regarding the current system and your "NUvi." I suspect the 2010 Nav system is considerably improved over a system offered in a car approaching perhaps 10 years old.
The new one is just as poor. There are many areas that the system will not navigate to. It is incredible that a $2000. system does not have as good a database as a simple handheld unit from WalMart. Lexus should be ashamed to offer such a poor product.