The game is called Civ 5, not Civ 4.5. Keep that in mind, and you'll enjoy the game.
With the graphics on high, it's ridiculously pretty for a turn based strategy game, but it also has steep system requirements. Rigs near the min specs will probably need to play standard or small maps.
It's a new game, and the devs were not afraid to take it in a new direction. I think this direction takes 2 main forms.
The first is, 'keep the turns moving'. This is done by reducing the amount of, let's say, *less important* info in front of you. When you select a unit, the options 'delete unit' and 'auto-explore' are hidden behind an 'advanced' tab. You just see the buttons you're going to use 98% of the time. Clicking the 'city needs to build something' notification just opens a list of things the city can build, it does not take you to the City Screen as before. When a worker is on a tile, the 'recommended' thing to build is a big button, the other choices are smaller buttons. So the game is all about reducing clutter and making the possible choices as straightforward as possible.
The other point I want to make is, the game wants you to stay in the main screen view as much as possible. As I said before, picking a new thing to build is done from a secondary menu to the left, the game does not leave the main screen. If you click on a city to get the City Screen, the camera just shifts position a little bit and focuses on the city, and menus pop up to the right and left. You can still zoom, heck, you can still zoom to cursor just like in the main map view.
In the City Screen, we see the 'reduction of choices' concept in action. When going to the City Screen for the first time, you can't move your workers from tile to tile as before. You have to click a menu, 'Production Focus', and then you can. Obviously, the game would rather we just picked something to build and go back to the main map, or at the worst, pick 'Gold Production' or whatever, let the AI handle the details, and go back to the main map. Once again, keep the turns moving and stay in the main map.
However, if you really want to move workers by hand, you can. In fact, moving workers is very well implemented, with the ability to 'lock' tiles you always want to work, so the AI won't touch them. But even here, once the player is satisfied that no matter what, that iron is going to be worked, he can get back to the main screen reassured he won't have to go back there again next turn and reset it.
I think these design goals are leading to the 'dumbed down' reviews and comments. The fiddly, obsessive Civ 4 micromanagement is still there, it's just that you don't need to worry about it if you don't want to, and the game would rather you didn't.
Once you accept that, you can enjoy the game. You can enjoy the parts the devs got right, like the tactical battles, no road spam, one unit per tile, Social Policies, and more.
(Yes, it's true the tactical AI needs work, and this might be the buggiest Civ at launch ever. When the Tac AI is improved and the bugs squashed, I'll come back and give it a 9.0)