I think there is a bit of Diablo thrown in the mix of WC3, as far as the heros go. The control is just like starcraft, the only thing that is really different is the units. I mean, it's more fantasy/midevil time looking rather than futuristic, they hack at each other with swords or shoot each other with bows and arrows and have dragons and such rather than space ships or guns, or fire bats...
It's a game that is worth buying. I haven't met an SC player that said they didn't like it to some extent.
The ladder system is way better on WC3, you have arranged team ladder, Random team ladder both being (2v2, 3v3, 4v4), there is a solo ladder, and a FFA ladder. It's a little more organized than SC. It's less repetitive too, I find that SC is a little bit predictable, and micro doesn't seem as important.
Look at it this way...
WC3 = Chess
SC/BW = Checkers
Little more thinking involved, but both are fun.