Here's my experience with it after only a couple of hours of multiplayer with some friends:
IT'S FREAKING AWESOME!!!!!
Since you didn't mention any specific problems you've heard about or explain what you mean by 'merits' I can't respond to your post except to give you my experience. And that is pretty much all subjective.
The visuals are stunning, I love the art design. I like the fact that instead of using black for the unexplored regions, they use clouds. I played Civ IV a lot but never quite got to the point where I knew all the ins and outs of strategy. Civ V feels more accessible for new players and those who were like me with Civ IV. There are advisors that will try to help you along the way, you can use them or not. The Civilopedia is great from my brief look at it. As usual the tooltips are outstanding.
Combat is, in my book, the best enhancement to the franchise. I love the 1 unit per tile mechanic (although if you want your stacks of doom there is already a mod for that). Combat feels more tactical than in Civ IV. You have to think about where you want to place your units, not just throw them all into one square. AWESOME feature: when Barbarians attack a worker or settler, they don't kill them; they CAPTURE them and take them back to their nearest fort. If your combat unit defeats that Barbarian before they get back to their fort, you RECAPTURE back your worker/settler. I loved it!
The chat box is MUCH better than in Civ IV, it has it's own box now instead of being part of the other notifications text.
My experience with the game was 95% positive and 5% negative.
After we had played 100 turns or so it was time for bed so the host of our multiplayer game went to save the game. UH OH! No Save game button. Apparently there is an auto save game button or something like that when you are starting the game but we didn't have that checked, so we lose our game. Seems like that should definitely be put back into Civ V. It was there in IV.
At the beginning I couldn't ESC through the opening cutscene until it was about a minute into it or so.
When ordering a unit to move you can't go back to that unit later and be able to tell where they are supposed to go. In IV you could click on your unit and a dotted line would appear telling you where that unit's destination was. This is the same for workers building roads across multiple tiles. After you've told your worker to build a road from A to Z, when you click back on that unit it doesn't show where they are going next after finishing the road on the tile they are on.
At the right of the UI is the score panel. It had a scrollbar for me possibly because of my resolution (1366 x 768). When I clicked on the scrollbar it went up and down like it should. However, later I realized that my mouse scroll wheel was not zooming the map like it should have and was instead just scrolling the score panel. No amount of clicking elsewhere, using different screens, pressing ESC would take it back to working with the map instead. I'm calling BUG on that one.
Again, I loved it though, and so did my friends. One of whom was a Civ IV junky to the max.