The 35/2.8 is less contrasty and the overall color that you can obtain with the same film is not as good. It depends on what you are after. Overall sharpness (which is about same) at a good bargain, or overall good color rendition and one full stop difference (at a much higher price).
The 35/2 summicron is just excellent, if you find a good and cheap piece. $1000 flat is a good price.