3 1/2 Stars, Civ4 was the better game.
Diplomacy overall is worse due to the fact I can't see any useful information.
Military is a double edged sword, more strategic and definitly better, however its a big headache moving a large army. After you've moved a 12 unit army you remeber why Civ4 added stacking in when you remeber that old Civ3 headaches you used to have, the same headache Civ5 now has again.
Economy overall worse, not being able to control which squares are next after each cultural expansion is not good in any way shape or form when your trying to make a city to specialize in production and hills are the last possible tiles cities seem to want to grow onto.
Game itself is far slower, with pauses between turns right from the start unlike the instant turns of civ4 (because the cpu's moved during the start of every turn rather then after.). Far fewer cities and units overall makes the game more boring to me, as I have considerably less to do. Overall there also feels like theres gaps in the content with no religions or such.
So maybe in a expansion or two the game might make me retire Civ4 for Civ5, but as it stands currently, its not even close.