Noticed a lot of good ideas. I'll start a thread here which includes my own ideas along with a multitude of others I agree with, and try to summarize everything (that I think, in my own opinion) can help to do nothing but improve Demigod. Just got done playing with a friend for 8+ hours to find I have work in an hour. Let's get down to it. :F Oh, a lot of these are dota-inspired, so incoming...
I can't stress enough on how little I have been playing this game. So if I'm ignorant and didn't notice a feature I just suggested, let me know so I can remove it! ._.
Interface
1. Toggle Demigod Healthbars always on
Terminology didn't really snap to me right away. Basically, an option where we don't have to hold down the key to show health bars to see them. :/
2. Friendly Demigod Portraits/UI displaying health
This would help oh so much, and make it much easier to keep track of allies and their health.
3. Friendly Demigod HP in Minimap
This would help as well, being able to see an allies' HP, thus helping you to choose a course of action.
4. Ability to select Demigods, or see their mana
5. Wider Demigod clickable frame
Not sure how to describe this, but sometimes the smaller demigods are a little hard to click when they're cluttered with a bunch of soldiers. It'd be nice to be able to target them a little more easily...
6. Interactive Mini-map
Complete with the ability to click a part of the map to instantly move your screen towards it, and the ability to right click anywhere on the mini-map to command your demigod to automatically walk to it.
Controls
1. Stop function or escape movement-path/cast function
Because walking in one direction shouldn't require you to go into another briefly to come to a stop.
2. Attack ground
So you don't have to initiate attack on everything, and allow your demigod to walk to a certain part of the map and not only auto-attack all incoming creeps, but push as well, while you briefly allow yourself to diverge your attention elsewhere.
Graphics
1. Make Demigods stand out more
They get cluttered into a mess of creeps very easily when the game gets into the meat of it all, making it very difficult to pick them out from the crowd. Something should be added to each demigod graphically, whether it be some kind of glow, or an aura representing their faction, or what have you.
2. Scenery
This is the only suggestion pushing it a bit, in my opinion, but the maps for Demigod are very dull. While the background, the characters, and all of the NPC's are beautifully done, theres not much else to look at but an endless void, and a brick road that swirls in random directions. Some new scenery/themes to the upcoming maps wouldn't hurt. For example, a forest with trees, or a mountainous field, or even a volcano with lava pools. Not only that, but actual things on the ground. Like rocks, grass, trees, bushes, debree, bodies, skeletons, dirt, earth, etc. Something to stare at inbetween each fight that isn't made of bricks. 
3.Bigger, more visible health bars
(Not the ones that show up in the corner when hovering over a demigod._
Gameplay
I haven't really played enough to judge this yet, buuut.
1. Faster losses
Losses need to be faster. They're painstakingly slow and supplement the losing side with a lot of chances to come back. The game goes back and forth and can last for hours if the gap of skill/in-game progression between either side isn't extremely significant. I guess there are a few ways to do this so far:
- Slower building regeneration
- Increasingly longer respawn times, especially when killed multiple times within a very short amount of time in base.
- Re-arrangement of maps so that regeneration crystals are much farther from citadels in conquest games and in general from the front of the base.
Multiplayer
1. Filters
2. Option to limit one demigod per team.
3. Arranged teams for Pantheon!
Coming soon...
4. RANDOM DEMIGOD OPTION
!
5. Friends/Ignore system
I'll edit it when I find/come up with more.