Worth Playing!
Gameplay
I found the gameplay to be highly enjoyable. Planning plays an important part of your city, since the layout is very much tied in to the economy. There is a chain of products between a resource that you farm or mine to its eventual form to the consumer (your citizens) and trying to lay out a logical city based on these product chains is fun and challenging. When thing I particularly enjoyed seeing unfold was in a mission where I was to supply Rome with wheat by sea, but I had to first trade for that wheat, also by sea. I missed several deadlines for wheat shipments, which the Roman senate frowned upon, even though I had 3 trading docks. Then I realized that my problem wasn't in my trading ships, but the fact that they had to haul the wheat all the way to the other end of my city to place it in a warehouse before i could ship it to Rome. So I planted 3 warehouses next to my docks, researched some tech that made unloading of ships faster, and voila, I had wheat flowing out of my ears :) This synergy of technology, geography, and economy is really what this game is all about, and the trick is to find the right balance to make a great city. All the while you still have to take care of your population, providing their needs so they stick around to keep the tech/geo/economic engine running.
Graphics
This is argueably the weakest part of the game. While I disagree with the Gamespy review that the graphics are 'ugly', they certainly arent very inspired. The main menus are pretty plain, but the do the job, and personally I care about the city graphics more then the menu. I would also note that their is a mouse pointer bug when playing at 1280x1024 where the pointer is offset from its actual position, causing you to click on neighboring buildings and not the one the pointer is on.
Sound
I like the musical score for this game so far, and I think the voice acting is great. Click on your citizens and they will give voiced comments about their neighbors as well as useful feedback about your city, like there aren't enough temples and so forth.
Value
I've played the campaign for about 6 hours now, and I'd say I've only uncovered about 30% of the content. The campaign takes you gradually into all the games concepts, and I have yet to get to the military parts of the game yet. Based on this, I'd say theres some good depth to this game, though I havent tried any of the 'sandbox' modes yet.
So to summarize:
Good engaging and deep gameplay.
Uninspired graphics and menus.
Good music and voice acting.
Whether this is the type of game I end up playing for a few days or a few weeks/months, remains to be seen, but though not flawless, I do enjoy it so far. I do think Caesar IV will be better, but this is a good game to tide you over until it is released.
Updated information:
I've played some more, yet another night staying up until 2:30 am :) Some more impressions, I felt I didnt spend enough time on a few gripes about the game that I hope will get patched.
Maps:
One original gripe was that the maps are too small. For the first 5-6 missions, this is true. Eventually you will get to a mission on Crete in the Campaign. This map is twice the size of the previous maps. The campaign builds you up slowly, giving you more options, responsibilities, and with those comes more land in which to fulfill those responsibilities. The game treats you as if you are a fledgeling city planner in the employ of Rome's movers and shakers, so hence you have to start from the ground up and earn a reputation by completing simple missions first.
Camera:
This is one of my biggest gripes. There is no way to adjust the angle of the camera. A top down view would come in handy often, but you are forced to rotate your camera around often to make up for this shortcoming. Its a pretty gross oversight in my opinion to have such a primitive camera angle system.
Citizens:
I saw alot of complaints about not enough visible citizens. This is only partly true. You do see all the workers, and the citizens do spend alot of times in their homes. They have children (including one that keeps picking a flower garden I placed and forcing me to put it down again). True, you won't see the masses of people that you see in a game like City Life, but then again, cities were not as big back then. I think the lack of citizenry is a factor that most buildings in the game take up alot of space for the number of people that employ them. Wineries, for example, only employ one person, as do most shops.
I still haven't gotten to the military portions of the game, and some have inquired about the map editor, there is indeed one, but I havent played around with it yet.