My Civ 5 Pre-order arrived last Friday, a few hours waiting for Steam to let me play it (damn worldwide release dates/times) and I got stuck into it.
First impressions: Ooohhh pretty
5 minutes later: Hmm, bit slow (PC well above min spec)
1 hour later: Ok, reboot and run it in DX9, much faster, less pretty
5 hours later: AI is kinda sucky, Tech tree is devoid of any path/variation, resources are devalued and dumbed down (especially food resources), tiles are dumbed down (flood plains=Grassland for example), Cities are far too easy to take even when defended by a unit, Health is no longer in the game, Global happiness, Embarkation feels a bit cheap and makes holding borders much harder, no way to change your Civ's Policies to adapt as the game progresses, Diplomacy is watered down, some nations are much stronger than others and make the game way too easy, the list goes on...
Ok, so maybe I'm expecting a bit too much, but to me Civ5 doesn't feel like Civ1-4 at all, I guess to sum it up, I still find myself playing Civ4 with different mods, or even vanilla BTS, I can't see myself coming back to Civ5 in a months time, let alone years after release.
They could have ported Civ4 into a hex-based map with the updated graphics, tweaked some of the silly things in Civ4 (SOD's, emphasis on religion etc.) and included the innovations like City states (which I have to say I only find marginally useful) and ranged combat (that was already modded in Civ4) and would have had a much much better game.
Meh, maybe I'm just getting old and grumpy, but Civ5 feels like a step backwards.