Alright I try to cover some areas that I haven't mentioned in detail yet.
SOCIAL POLICIES
They're there and as far as I could see there is no way to change them. Which also wouldn't make any sense, since some of them give one time bonuses, like the Great General you get through the Honour branch.
My impression of the Social Policies at first was that they are intimidating. There's a lot of possibilities and your choices matter a lot. You don't just fool around but have to plan your strategy wisely. I think this will make for really complicated decisions in a real game, as I was just testing I just dumped them somewhere to have it done with.
So I'll just assume you know what the branches are and what is known about them by now. If not check out Ariochs site:
http://well-of-souls.com/civ/.
I looked at all the Policies and liked what I saw, unfortunately I won't be able to remember all of them though. I can think of those that I found most interesting though.
TRADITION has a policy that makes your units fight better within your territory, making this ideal for small empires who want to defend themselves.
The PATRONAGE branch there was one policy that will keep your Influence with City States above a certain threshold once you have reached it. This is welcome news as I found it quite hard to hold on to City States.
Und AUTOCRACY one policy gives you a flatout 10% increase in unit strength across the board. If you want to war, this is your policy.
RATIONALISM just gives you tech everywhere, one policy gives you +1 tech for every two citizens in every town that has a trade route to your Capital.
The rest really enforce the theme of each branch. So I find those choices you have quite daunting and interesting. Have a lot of land and want to grab it quick, take the Liberty branch and just expand away. Find yourself boxed in but with some decent spots, go all out on the Tradition branch and then add the Freedom branch later to really boost that Specialits Economy of yours. Have no land and a crappy starting position, just hang in there until you get to Autocracy and just warmonger your way to the top. Your units are 10% better than your enemy, even with equal tech you are superior, it will be quite hard to fight you indeed.
It's those choices that make the game really interesting to me and I like how the Social Policies enforce this mindset. Of course it was nice to mix and match according to the situation in Civ IV and from a realims point it is utter nonsense, but I like the gameplay implications and really look forward to the different strategies and synergies during a full game.
TECHNOLOGY TREE
Maybe I'm just not used to Normal game speed anymore but man did those discoveries fly by. Most technologies were researched in under 10 turns and I didn't focus on science at all. With the slider gone it is hard to tell what you are focussing on though. Science just seemed to happen without me having anything to do with it. I actually even forgot to check where all that science is coming from. I easily had a situation where I had far more buildings to build than I could possibly complete within time, I remember in Civ IV on the lower difficulties I would run out of build options before I discovered the next tech. This did not happen here at all. I did build several units though, especially as the Germans, so maybe that was the case.
The technologies themselves are always quite useful. The ability to chop now comes along with Mining and you can build Watermills after you discovered the Wheel (they give +2 food in the city, the city has to be alongside a river though). So there's a lot to do with the early techs already. Calendar for plantations and Optics for the ability to water are reached very quickly if you compare it to Civ IV where both come a tad later. All in all I'm impartial to the technology tree, it has to be seen how you fare on higher difficulties with it.
IMPROVEMENTS
I think here I'll cover city management as well. Improvements are different from Civ IV in that they give far fewer bonuses initially, especially on ressources. Cattle improvement is only +1 hammer and farm on wheat is only +1 as well. So you won't see those initial 5 food tiles you're used to getting from IV. Fishing boats on fish give +2 gold (food remains unchanged at three) of all things. So this felt really new to me. There are several technologies and Social Policies that improve the output of farms and trade posts though. They add money or research to the Trade post or add food to the farm when it is connected to a fresh water source. On the flipside fresh water is not needed to build farms. Felt weird to just plaster that Dester Hill beside my capital with a farm. Looked much greener afterward.
So going from this I only had a few workers and didn't feel like loosing out all that much during my plays. In the end this also had to do with the fact that what your city does is actually quite cleverly hidden from you. Unless you specifically seek it out you can just not care about tile allocation for example. Once you get to it though I was further hindered by the new icons. We know about them for some time now and I think they look nice, but it is really irritating. So green stuff is food now and red/orange stuff is hammers and the blue stuff, which was hammers is now tech? I guess you just have to get used to it, but I really miss those little wheat icons and hammers as opposed to the new apples. It really made it hard for me to see at a glance what tile produced what. Maybe I'm just very unflexible.
Apart from that the City Screen is very well divided and let's you get to all the necessary things quickly. Citizens use up two food each by the way.
LOOK AND FEEL
With the UI already mentioned with the improvements I'll move on to the general Look and Feel. The UI really is very streamlined without loosing the functionalities it had before. It was so streamlined that I completely forgot to check up on some things (what exactly is my science rate anyhow?) as everything was running smoothly and I was more focussed on killing barbs and over all enjoying the new game. Animation and landscape looks nice and fluid. On the computer I was running you could often see a change in resolution though. Especially when the AI contacted you they would start of as low-res for a second and then move on to the actual resolution. So probably some kind of loading thing, sounds good for weaker machines, but would be a bit annoying on a regular PC.
And while the hexes are easy to use it took me some time to get a fell for the landscapes. Often I would expect hills where there weren't any as I hadn't gotten used to the new hex grid. I had to turn the overlay on to get a clear picture, whereas in Civ IV I am so used to the grid I see it even without the overlay.
Moving units is very intuitive as well. There's also the possibility to have units switch places, even over a distance. I once moved my warrior two tiles right on top of my Chariot Archer (which I didn't see as my Great General was on that tile as well) and the Chariot promptly moved two tiles to the position my Warrior was in. So handling your units works fine even with the 1 UPT. The only time it got a bit annoying was when I attacked a barb encampment on a narrow peninsula. But then it is supposed to be harder to navigate chokepoints. If the barbs had an Archer along with their Brute it would have been quite hard to take them out!
I'll add this along with the MISCELLANEOUS section to my original post as well. It's all I can think of right now, but I'm sure I forgot some things as well. Really irritating to find out later how I obviously completely forgot to check some things. I was just so busy playing I guess. It was just marvelous and I tried to soak everything up. As an avid Civ IV player I look forward to Civ V and will get it a release day!
One last mention goes to the Civilopaedia. It's just ginormous, serously! The Game Concepts page alone probably takes two days to read in its entirety. And the history sections are just amazing. I checked out Germany and you could scroll down like four to five pages where they told you everything, from the barbarian tribes, to the Romans, to the Holy Roman Empire, to the Reformation, to the Napoleonic times all the way up to the present. So if you want to have a history book along with your game Civ V seems a good choice.