Might want to try a demo or a friends copy or something. Civ 3 has some interesting stuff, especially interesting is tactical resources. Also interesting is workers taking population.
Otherwise its rather sideways move from civ 2. Some stuff better. But I think when making civ 3 they decided simplest was best. Which they took a step too far. Large grid squares, simplified terrain, well not much different then civ 2 (larger grid then civ 2 I think though) but nothing like the nifty terrain complexity of alpha centuari.(a good spin off of civ 2) Other little stuff like the unit attack/defense system and hp based on skill that screams oversimplified to me. Few game mechs of civ 3 are truly revolutionary in any ways.
I've heard civ4 is in the works. You might want to wait till it comes out. I feel like maybe I should have. But its all personal preference. Which is why you want to try it out for yourself before you buy it.
Oh, if you do buy it, find and buy the original game and the conquest expansion separate. Don't bother with play the world, its in conquest. Its generally cheaper then buying civ 3 complete.
Also, reading the forum for CTP, seems a number of people liked CTP2. Worth a look maybe.