Great Weapon Master (GWM): Please please stick to the 5e rules and make it optional to use. GWM's efficiency is always dependent on the characters to-hit modifier and the enemies AC. Especially in early levels a forced -5 on hit is really hurting
You can already toggle GWM effect on/off in the reactions box. The UI will certainly be improved at some point, there's been several other elusive UI elements that I've found by accident or read from forums.