My SL has the following radio, BoseŽ audio system with AM/FM/in-dash 6-CD changer with 9 speakers, Radio Data System (RDS), and MP3/WMA CD playback capability + XM. Maybe US models are different.
As for the tag almost left in the car, no big deal as it wont let you lock up. The keyless ignition is actually very nice after using it for a while and a very secure system.
The brakes are very smooth and powerful, I've had to use them in a tricky situation(deers) and they will stop this car quite well, also I would suspect they will last longer that typical junk brakes on a GM car.