I mean, I have to agree that the user interface, well, sucks... But it's not even in my list of top 25 things to fix. I'd much rather have something to do.
As you say Dale, the immersion is lacking. Nothing about it feels "epic." Sure, the UI blows, the AI sucks, and production is too low. All of this has been mentioned repeatedly. But Civ5 got all the little things wrong too. Everything from the music (snore) to the top ten lists of nations with the Most Pointy Sticks. Really? Most Pointy Sticks? Who thought that was clever, funny, or even remotely epic.
The intros for the various civs are awful. One of them "asked" me if I could restore my people to greatness. Restore them to greatness? I'm not restoring anything; I'm creating from scratch. That is the ENTIRE POINT of Civilization. Hell, even the white fog of war is stupid. The civilized world is supposed to be a beacon of light in the darkness... not a break in a heavenly cloud. The quotes suck. Could they be more obvious? Instead of riffing off the technology or whatever, they explicitly reference the discovery in the most tedious, dull way. Where's the wit, the charm, the epic sweep of humanities achievement? Did I mention that the music was bad?
These all sound minor, but they add up. There are many (many) gameplay problems, but the atmosphere is all wrong too. Civilization demands an epic feel. You have to unleash your inner Cecil B DeMille when designing a game like this. I suppose you could lump me into the category of people wanting another Civ4, but I don't think that's accurate. It's just that every single decision they made with Civ5 was wrong. Every. Single. One. For the life of me, I can't think of a single thing Civ5 does better.