So I thought I'd post my impressions based on my first introduction to the beta. I will of course list out seperate bugs and suggestions in the beta 3 thread, but I think (hope) this is the right place for overall viewpoints which are hopefully useful to the developers.
Overall, there is the core of a really good game here. By final release I think this is going to be a good, but not yet a great game. Here's where I see the main opportunity areas (I won't focus on technical aspects like stability, which sucks, that belongs in bug reports).
Major points
Tactical Combat - It looks to me that the make or break for this game will be the tactical combat. Building up an empire and designing units is fun, but only up to the point of seeing it in action. Without meaningful combat (i.e. being able to see and understand how your choices played out), it all becomes something of a stat building exercise. Since we haven't yet seen this aspect, I'll leave off there, but from a gameplay perspective this is the biggest prioirity.
AI - The second priority. Again, it's not in beta 3 so not worth major comment, but this would change the feel from the beta to a game. Today, you can wander around aimlessly without fear of interference. Tomorrow you need to feel like you're competing and taking risks. Obvious stuff.
Cities -These aren't there yet, and it's been posted by others. There's no real feel to them. The layout doesn't matter, so why have one? I think there is some effort currently going into this on contiguous building (though I can't raze anything currently - is this a bug?) but cities in general need some more to them. There is already a good suggestion about gaining city traits as they increase size which I won't repeat.
The layout also needs to matter more with respect to building defences. For example; a hedge wall should not be a 2x2 improvement, but a wall around the city - you choose where to build it and pay per 'square', determining whether to leave space inside the walls or not. I can see problems for the AI here though, so perhaps it is your intention to convert the 2x2 into a defence in tactical combat; in which case, choice understood. Nevertheless, the general point on city layout and shape feeling a bit pointless would still remain. At first I was irritated by the glitch that when I clcked on the city to build in a certain place, it would 'jump' and build my improvement in a different place, but now I've ceased worrying for the reasons above. I'm not sure that was the desired intention though!
Minor points
Magic - The system is very opaque. I know you're still settling on this one, but as a first time player I still don't get the differences in essence, mana, spell points and how they all work, and what actually improves them. The value of shards, which seems to be a hot topic, also seems underwhelming, as I can have dozens (or more?) spells and cast them, even without shards. Are shards doing something else for me? It's a bit unclear, and I don't think you want players to have to read a full manual to grasp some of these basics.
UI improvements - Map; still some clarity needed on the map. Roads should show up on the cloth map. Icons for things you can't use yet/enter, should be more clearly displayed differently (used inns, dungeons you can't enter, etc). It might also help if newly discovered sources of interest 'glowed' or something for a few rounds (I will post seperate suggestion threads for these). At current, I travel to check Inns I've already checked based on the fact that some innns with the same icon do nothing, so I can't tell which are new and which are old. I also travel to dungeons and nothing happens for the same reason.
UI improvements - Other: one of the joys of this type of game is watching your developments grow, both visually and more stats based, so we need to feed players the information more easily. Key data, like a character's current base stats, experience, etc need to be a lot easier to find - where can I check my dexterity score? Why is xp hidden in his notes? The same is true for cities - a city listing sheet with each city's production on it seems critical (again - will post the suggestions in the beta thread)
That's it for now - tried to stay reasonably focussed. Hope it helps...