Hi there! Elemental is really starting to take shape. The improved AI seems to have made a real difference...i now feel challenge and therefore I feel like I am playing a game. Here's some quick thoughts on the game after playing the new beta
Civilisation - The resource system works very well in my opinion. My main suggestion at this point would be to include some upgrades that can increase the growth rate or influence of the town significantly, but for high costs. At the moment, you place down a city, and it will slowly grow to gobble up the surrouding resources. This is fine, but should an enemy place a city next door, there is no way currently to shove his border back off those resources, bar a few unique wonder of the world style upgrade or direct warfare. It would be nice to be able to pour money or resources into the settlement to expand you culture, at the expense of potentially upsetting your neighbour diplomatically as in Gal Civ. Heroes, agents, spells, or city upgrades could all be good ways to add this. Without this, the civilisation aspect seems less strategic and more a case of making sure you have built enough houses so they can grow.
Warfare - Two thoughts. Firstly, at the moment I find warfare is the most powerful and interesting tech tree. I don't normal play 4x games in a militaristic fashion, but at the moment I am more or less encouraged to by the game. Tough roaming monsters threaten cities from the outset, important heroes need outfitting and protecting, and the other trees don't offer the same power or variety to do this. It would be nice to see the Adventure tree add more upgrades to heroes, such as unlocking more weapons in the shops or giving global buffs, and it would be nice to see magic feeling more powerful in combat.
Secondly, I don't like how each enemy gets infinite retaliations in tactical battles. This seems to make certain units feel weak or useless, particularly the non-hero melee units, as they tend to hit for 1 or 2 damage and then immidiatly die to the retaliation. Other units, such as archers, become very powerful as they don't suffer retaliations. Also this encourages the player to build heroes with one single, powerful attack, rather than lots of fast but weak attacks, which i feel should be equally good strategies. At the moment I found the most effective way to win tactical battle was to kite the enemy, using peasants to block their path,while archers and casters shoot them, and then finishing them with a powerful attack from a hero. Retaliations need to be limited in some respect so they don't just feel like the enemy has a powerful damage shield.
Magic - I have not explored the tech tree very much, mostly because I seem to get a good variety of spells very easily from the outset through arcane research. Mostly I am finding the utility spells to be very powerful, such as teleport, and enchantment buffs, whereas the combat spells don't seem powerful enough to justify their use of my mana. But that might just be air magic 
Adventure - I like the quest system and it's going to be my favourite part of the game when completed. Right now though, I don't like how easy it is to lose heroes without much warning. You step on a harmless looking goodie hut, and suddenly you are in a fight with a load of giant spiders which you can't win, wiping out all that hard work. Equally one hit from a tough beastie can kill a hero - so you might win the fight but you have lost your soveriegns husband
Heroes represent a big investment, and shouldn't be easily lost to bad luck. I think that the Adventure tree should not just unlock dungeons, but add survivability to heroes....let the escape, be rezzed, or make them tougher, so that investing in this tree makes you more confident in sending your precious units into scary dungeons.
Diplomacy - There is a nice framework here, and its going to work well when completed. There needs to be a greater variety of ways to gain diplomatic capital, but I think overall this is going to be a crucial part of the game, particularly with the way roads and trade work.
Keep up the excellent work!