Electrical woes is about the only bad things I have personally heard about them, as well as extremely expensive repair costs.

My uncle has a 1994 S500 sedan- when his A/C went out, it was a $2100 repair. . It was given to him by his father last year when he bought a brand new 2004 S-Class sedan (I think it is a S430?), so he only has that much invested.

Good luck to you.