I have a truly crappy computer and turns times are not nearly as bad as people complain they are. It was much worse for me in Civ4. And that was with a better computer.
I've played both Civ IV and Civ V on this laptop, which is newer than Civ V, and Civ IV is the faster game.
The fortify button should be in the main controls, the advisor button should go away, and the game should save your interface settings between loads (it does for some things, but not others.)
So? The game isn't perfect, but the fact that you have to resort to complaining about minor UI mistakes means that the game is excellent. I just suck it up and hit the extra button to fortify. And that is the only thing that takes longer to do in CiV over CIV. The rest of the UI is better designed. I took more time trying to find the buttons in CIV.
I'm a fan of Civ V, but it's exactly these kinds of minor annoyances that shouldn't be understated because they're often the things that put people off to begin with - as in everything first impressions count for a lot. Something as trivial as renaming the Civilopedia the more generic "Help" in the main interface is a clumsy loss of flavour where none is needed. Simply the console game look of the interface put me off for several months, and I'm a lifelong Civ fan since the first game.
I had problems with the Civ IV interface as well, naturally, though many of these were visual rather than things that affected utility.
Again it was ugly, and in that case the main page buttons were too small, numerous and cluttered to be useful as quick access. Some certainly could have been dealt with in sub-menus or tabbed pages, as was the case in previous Civ games.
The central placement of the unit commands was unintuitive, as most people will default to mousing towards the left most of the time (but not as far as they need to to use the Civ V unit menu).
In general, Civ V has a better city screen interface (although I miss the food store). Showing net production in the main view rather than '6 food produced - 4 food consumed' is an obvious change that should have been made years ago.
Though it took a little getting used to, a city bar that actually shows turns to production and growth is a clear improvement, and it's strange that it took the Civ series so long to institute something that's been a standard of, say, the Total War series for well over a decade (i.e. numerical values displayed for relevant city traits).
As for the diplomacy screen not offering you a chart of people's relations with each other, I think that was a design decision. Now defensive pacts are sort of secret pacts. Is there anything else that chart ever gave you?
Making the interface look like a cheap console game is a design decision. Civ III abandoning the 'stonewashed' interface background was a design decision. Losing the We Love the King Day palace was a design decision. Including Cristo Redentor as a Wonder was a design decision. Design decisions aren't always good decisions.
It's not about providing new information, it's about the way the information is provided - and especially since interciv relations between your rivals are more important to keep track of in Civ V than in any previous version of the series. Yes, you might get a moderate negative modifier for upsetting an ally's ally in Civ IV, but it wouldn't dictate your relations with a third party as it does in Civ V. If I visit the Global Politics page in Civ V, I have to scroll through 10-12 civs to identify who's friends with who, who's at war with who, who's denounced who... and then I need to switch to the default diplomacy page to identify which civs are allied with which CSes.
In Civs I-IV, I had a single colour-coded web right in front of me that gave me all the relevant information at a glance. CS relations could be included either along the top/bottom of the same screen as the CS name together with the icon of its ally (if any), or by putting an appropriately-bordered CS icon alongside that representing the civ it's allied with.
That also saves space on other pages, potentially enough to reintroduce the extremely frustrating omission of a 'tradeable items' page - as it is, you again have to scroll through every civ and every CS to identify what its trade goods are, and there's no way at all of seeing which resources they already have (so aside from occasional advice from the Foreign Advisor - on, naturally, yet another page), you don't know if they already have what you want to offer). The fact that nothing shows your active trade agreements or the length of time any given agreement has still to run is also a simple irritant with the interface.