So I've started playing the beta, just bot matches so far, but one thing that really bugs me is the map layout. I know it's highly regarded but it is something that was clearly designed when 4x3 monitors were the norm. The big issue I have with it is that right now the GUI in the game takes up a lot of vertical space, but most of the gameplay of the early game for the side lanes takes place on the vertical plane as well. This results in things feeling very cramped, meanwhile there's a lot of space on the horizontal that's just going to waste. Now this will change over the game, but for the early game I really think it should be avoided when the designer has direct control over where the engagements will occur. A fairly simple change would be to mirror and rotate the map as shown below, this puts the long lanes on the horizontal and not the vertical and allows the the engagements to take place with the most visual space available.
I realize the Dota community would never support it, but I feel this is a way in which the game is being hampered by being beholden to them.
They also really need to get GUI scaling/customization in.