I've got the 45z. Bought it after reading comments and hearing bigwalton's 40z. I have been very happy with it. I can now hear parts of of songs that I never knew existed before. Aesthecially, its basic looking (which I like, it doesn't attract thieves), and looks like it belongs there.
As for for the CD-R's, dnewma04 is correct, the cheaper CD-R's don't seem to play, but all others I've had no problems with. Just don't buy the cheap 100 pack no-name stuff and you'll be fine.
