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I'm not going to lie, SC2 always looked "neat" to me but think of the modding potential it has, with the games popularity there's going to be some awesome stuff, I'm already seeing FPS mods rising up as well.
The modding potential is good enough for me to buy the game. My one biggest annoyance though is the Starcraft theme itself, I'm just not feeling the Sci-Fi atmosphere and hope we'll be able to use our own custom sprites and textures for the custom games (WC3 had a little support for this). I'm looking forward to some good tower defense games mainly (although won't be a day 1 purchase for me, maybe a few months down the road)