As a side note, this game was fantastic in the brief time that I played it while it was in early access. To any Tiger Woods PGA Tour fans, this is great fun.
There are four reasons why everyone that I know who plays civ is getting this: Tech web, better balance, better multiplayer, and better AI. Science in general is far, far too OP in Civ 5, and I think a big reason why is because everyone has to go for the same techs, so whoever gets there fastest is usually able to reap those benefits more even if thats not their focus (cultural and military things especially).
But really, as long as the multiplayer is even half as terribly made as it is in Civ 5, its worth the $50 to me.
RIP SSX :( I really enjoyed the last game, though i dont know what the general consensus was.