1. About how long does a game take to finish?
 
2.About how different is it from civ rev (360 version)?
 
3.How hard is it?
 
4.is it worth 60$?

Coming from Civ Rev it is very different in terms of specifics like specific wonder and building effects, but a lot of the core concepts are the same. It's just got a whole lot of depth that you can come to appreciate. It's much more complex, there's a lot more to think about. It doesn't have that cartoony art style. Its much more realistic and serious in tone this time around.
 
I'll let others answer the rest.
 
Edit: Also, just try the demo out. You'll see how it runs on your computer and get a feel for the game.

1) You decide the game length, you can have short to long games.  Its configurable.
3) Same thing - you can configure the difficulty.

" 1) You decide the game length, you can have short to long games.  Its configurable. 3) Same thing - you can configure the difficulty. "

Worth $60? I'm considering buying a proper PC for it! That'll be like €1,500. But yeh the demo alone has me hooked so it seems well worth it.

Thanks guys i think getting the demo will be the best way to go and see how i like it

"Worth $60? I'm considering buying a proper PC for it! That'll be like €1,500. But yeh the demo alone has me hooked so it seems well worth it. "

Buy it from Direct  2 Drive, cost me 30 bucks instead of 59 euros!