Played 50 hours of civ 5. All I can say is a pretty game, but not solid enough for being a great civ game, in my humble opinion.
The game appears unbalanced, with an AI that is clearly stupid and no match even at highest levels. The strategic management is overly simplified for a CIV game (but I see that most enthusiasts appreciates this simplification, perhaps they simply don't like all the management fun that made great the CIV serie).
My thought is that this is a tactical war simulator with beautiful graphics, but a very poor AI, intended above all for noobs of strategic games.
All the strategic aspects seems to have been neglected, or striped out, causing a boring experience for the expert player that have no fun to happily slaughter an helpless AI.
Furthermore, the game appears to suffer still too much bugs and random crashes that spoils the fun (On a very stable W7 system, with a powerful pc and graphic card, and updated drivers).