I use a Razer mouse at work, and it's still going strong after five years of heavy usage. So, like anything, YMMV.

To be honest, even if they only ever lasted a couple of years, I'd still buy Razer mice. All non-gaming mice nowadays seem to be awful, cheap crap, and most gaming mice are over-decorated contraptions. Razer mice seem to be the only one they combine good, simple ergonomics with high precision and a quality feel.