After playing a few games with a friend, I'll give some feedback.
-You should probably increase the preparation time by like 5-10 seconds
-Add Hotkeys for Builder skills, (Move unit, Sell unit etc.)
-Yeah units sometimes disappear, you should make the placement zone more accurate (They also don't combine sometimes)
-About balance, In the later rounds it turns into AOE fest, it just comes to who has the strongest AOE heroes (Ner'Zhul, Ignius ...)
I would love to see an increase in amount of players, playing 1v1 is fun but, the more the merrier.
3/5 for now, has potential.