For me the tactical battles could use a little bit of fixing, but frankly that ranks up with enabling multi-player for me and thats not very far.
First things first is that the stability and memory leaks need to be fixed.
Second the game needs to be fleshed out in several ways.
1. Revamp the magic system with distinct spellbooks and way more spells. Also change essense into a channeling ability and make spells take several turns to cast depending on your essence. Oh and lets not forget they need to fix the spells they currently have like drain life.
2. Next the game needs more models.. i.e. We need more npc's than a dragon, golem, wolf, spiders, a lizard and humans. Oh I nearly forgot Ogres. How bout skeletons, ghosts, vampires, lizardmen, draconians, faeries, elves, dwarves etc.. you get the idea.
3. Then fix the AI, its easy to beat the computer now, because all I have to do is fortify one city then wait for the leader to invade my city suicide style.
4. Then open the game up to the modding community through python etc...
Then they can work on fleshing out the tactical battles and making it more epic as some are complaining about.