Personally, I thought Civ V was pretty meh. Now, if you really want the best drug the gaming world has to offer, get Civ IV.
Sid Meier's Alpha Centauri is an even stronger drug... Planet awaits...
Yeah I to thought Civ V was a little underwhelming, the hex tiles are great but I think the one unit per tile (or two if you have both a combat and non-combat unit together) becomes a bit impeding when you have a whole continent full of units! This has happened to me in the later stages of the game.
I also feel Civ IV gave a greater sense of change through the eras, plus the music was amazing.