I also thought SC2 was too much like the original, despite not being a big PvP fan (as in, melee or un-modified gameplay). The graphics are nice, and there are hundreds of little tweaks that make full use of the AI and make building and such, painless.
I almost exclusively played UMS maps, minus a few attempts at the campaigns (never finished them, much less without cheats). Loved RPG and defense maps to death, though. Looking forward to the editor, since it's supposedly extremely flexible (and just waiting for some ample and creative hands to fondle it).
Still iffy on if it's a day one purchase, but I don't think Blizzard will let us down.