The interest for me is the challenge of getting it working,putting the features that i require into it and
using it in my project which requires a fast cpu and i can build into the FPGA which holds a lot of the other project components.
If you were to target it at an altera or xilinx device it would use the built in multiplier/rams and I happen to know that a full 6502 fits into a ten thousand gate Altera FPGA as i used to work for a company which sold such a design.
I think soft processor cores are the way that the industry is going,if you look at the virtexII+ they contain 4 or more power PC processors as a hard core and they sell like hot cakes.Xilinx also offer the Picoblaze and Microblaze 8 and 16 bit processors as a soft core for their coolrunner FPGAs so its something which you are going to see more of I think.