Shadow Sun ninja is a lot of fun, but it tends to favor Shadow Hand and Setting Sun maneuvers. The idea behind it tends to be 'balance in all things' as a sort of philosophy. Not so much embracing evil or negativity, but more 'dark is not evil, and the shadows can be useful'. It's certainly a flavorful prestige class, and the requirements for it I believe make it so that you MUST be good. If you wanted to go into it, you're more than welcome to.