The feel of the game
There are a few issues regarding balance and game mechanics but every game has them and games like this tend to have massive changes through their life span so we can expect that all to change without even acknowledging the fact that this is just a beta.
The real thing you guys should be focused on between now and release (my opinion as a player) is the feel of everything. The way the game looks and feels as you control your character. Does it feel like I am in a team fight working with my friends to keep our foothold in this match or does it feel like i am watching someone else move as my pawn while I simply stair at a tv screen telling them what to do.
Right now its less me and more some character that I have no care for. That being said, I said the same thing to Blizzard during the beta for overwatch and now that game is as fluid as a raging river. I am excited to see what happens with this game. I see tons of potential to make something of this game, which should scare you a little because with potential to succeed comes potential to disappoint.
P.S. a couple specifics would be working on the evasion mechanics and lock on and how certain abilities behave with that particular mechanic.
Nice post! I made something similar back in the Alpha forums, is this similar to what you're saying and something you agree with? https://forum.bleedingedge.com/topic/337/some-ranged-abilities-feel-lacklustre
Interested to hear your thoughts