I still suspect the reviewers were bribed somehow, or perhaps tested the game before it got radically dumbed down, just before release?
I think the glowing reviews of Civ5 are explainable without resorting to bribery or shenanigans by the developer as the cause.
I am a long term but relatively moderate Civ player. I've been playing since the first Civilization and have played all of them since then. Including Civilization: Call to Power and Call to Power 2, plus Alpha Centauri. And all of the Master of Orion games (including 3, regrettably) Master of Magic, and GalCiv and GalCiv2.
I am not an expert however. I can't beat any of them at the highest difficulty settings, with the exceptions of the original MoO, mainly due to Sulla's recaps and videos.
When the initial Civ5 news stories came out i was wary about how the one unit per tile thing would work, however when i first got the game i have to admit i quite liked it. It was simple and easy to get into and it was very pretty. And i've always liked one city challenges, it it made those really easy!
It took time to realize that perhaps it made one city challenges _too_ easy, and did so at the cost of making other styles of play (anything involving more than three or four cities) prohibitively difficult/unrewarding. Doing the tactical combat was kind of fun at first, it took a little while for the problems with the combat to become more clear. I did notice the dearth of interesting buildings and how long they took to complete much earlier, but i didn't really make the connection to 1UPT until it was pointed out by Sulla and others. I'm sure those problems were immediately apparent to the real experts, but for the rest of us it took a little while.
Reviewers generally don't have that much time to invest in playing a game for review. They saw the pretty and got to experience the first dozen or so hours where it was fun and easy, but with enough choices available that it seemed to present the kind of strategic depth that would allow for a great deal of replay. They never got to the point of realizing that most games end up being the initial rush to build your first two or three cities and then just sitting back and hitting "next turn" a lot.
So they gave their reviews and left it to the Civ community to do the in-depth analysis and rip it a new one.
But those initial reviews were probably correct for a lot of people. Civ5 _is_ a great game for people who want to put in a few dozen hours without facing a serious challenge and then move on to the next game. Or people who like dumping in a lot of time into a game that's at least moderately entertaining in order to pick up achievements. (I confess that i got sucked into that for longer than i should have.)