Completed a quest and gained a red dragon as an ally. Awesome. Went into a tactical battle and he was huge and awesome and well just a bit to big. Couldn't see any of my other units since he was so big and hard to see through. So I recommend making really large creatures smaller. Huge creatures in a tactical battle, although visually stunning, are not easy to manage on a practical level.
Second, I don't like the huge giant squares used on the tactical map. I would recommend either smaller squares or hexagons or octagons.