Trilarion: Really interested. What underlaying issues makes it so fundamentally boring to you? I thought for once that the one unit one tile concept is nicely done and the overall happiness and social policies are also interesting. Some things are easier than in Civ 4 and multi player mode is a bit difficult to use, but compared to titles from the 90s, the ones we are dealing here, even the Civ V multi player mode is fully functional.
I could probably write essays in reply to that question, but I'll try to keep it short. ;) The main reasons why Civ5 bores me are: less choices, too much focus on warfare, inept AI, too much focus on "winning", horrible interface.
The way I enjoy Civ games most is this (taken from my usual Civ4 games): I mod the game to a super-huge map with about 30-40 civs, more technologies, more units, and a better UI (BUG mod) and AI (Better BtS AI mod). I then play the game very slowly. I name my units (especially when they won decisive battles), I name landmarks, I used to enjoy looking at the statistics (there was a mod tracking statistics for every single unit). When I meet other civs, I act in an historically plausible way even if that isn't the best way of winning the game - while I like to win the game, I wouldn't enjoy it that much doing so at the cost of my immersion. I try to understand the personalities of my AI adversaries and react in a historically plausible way towards them, having all the data about why they like/dislike me helps a lot with that, in the same way as the numbers of pen & paper RPG characters help me to tell plausible stories about them. I regularly browse through my cities and just enjoy looking at them and imagining the life there. I like to have _tons_ of possible decisions to make at every point in the game, I like to juggle with dozens of different plans and concepts at the same time, and Civ4 is one of the very few games that allows me to do that with the degree of complexity that I enjoy most. I rarely choose slavery as a civic (even though it's often superior strategically) because I don't want my citizens to be slaves. When entering a war, I often try to keep it short, wars are more boring to me than building up a civilization. The stack-based movement system helps a lot with that since it allows troop movements and fights to be quick, so I can focus on the parts of the game that I enjoy more. My games usually take about 3 weeks; it's possible that I discover during the second week that the game is unwinnable (since my games are so huge, a runaway civ on some of the many other continents is a possibility), but that doesn't impede my enjoyment. I then set my goals the same way a real historic leader would do under such a situation, and continue to enjoy being a part of an unfolding vast and complex alternate world history. When the game has ended, I particularly enjoy watching the history replay, reliving that history - this takes about 6 hours usually (since I really read it completely and keep track of the changes in all parts of this huge world) and is always a part I look forward to.
From my perspective, Civ4 was a great base for such a gaming experience. It wasn't quite complex / slow / detailed enough, but mods changed that. In any case, Civ4 seemed to have been developed with basic ideas that supported my preferred playstyle very well, and it's a playstyle that very few other games have ever managed to cater to. (That's one of the reasons why the wargamer department wasn't too fond of Civ4 btw, it didn't really cater to them.)
Civ5, however, seems to have ripped out (or at least severely reduced) all things that I enjoy, and replaced them with stuff that I either don't like or don't care about. 1upt puts much more emphasis on warfare and tactical movement, but at the same time the AI is so bad that it doesn't become challenging, so I spend a lot of time fighting boring battles. Diplomacy has been severely reduced, there are no stats and values that help me telling my stories and immerse myself in the alternate history, everything is kept under the hood and for the most part the AI's decisions seem very irrational. The AI will backstab you because it tries to win the game instead of you, which destroys immersion since the whole "winning" part has little historical plausibility. There are much less choices available at any given point in the game, I never get to the feeling that I can juggle dozens of decisions at the same time. Instead, you typically make one decision at an early stage and are then locked into it. On top of all that, the UI is a chore to work with, getting necessary information turns into a clickfest and getting additional information (that would help my immersion, as explained above) isn't available at all.
Now, it's interesting that you draw a connection to other 90s strategy games, because when compared to games like Master of Magic or Alpha Centauri, you can see that Civ5 inherited the bad parts of those (bad AI that can't really play the game), but not the good ones (lots of features, lots of different things to do). In the 90s, 4x strategy games added lots of features, but it was impossible to write an AI that could actually understand them. Civ4 was a pretty successful attempt at writing a complex 4x game with a competent AI (though there's of course still room for improvement). Civ5 seems to have been designed as a game that reduces non-warfare complexity in favor of enhanced tactical gameplay, which then failed because the AI wasn't able to play the game.