Definitely one of my all-time favourite villains. Even the movie version was quite cool, in his own way.
But this was certainly an amazing fight. I love the explanation of how the Shredder keeps on coming back from the dead - It makes perfect sense for a comic book and could even have it's groundings in some real-life pieces of mythology and magic. The fact that Shredder also has three screw-up versions that he keeps around was brilliant, too, and the rest of the Turtles fight against those is also pretty darn awesome.