The biggest problem I, and it seems everyone has, is the level cap and this is not without reason.
I think most people, who have any knowledge about 5e will tell you, that the level cap is fine. The things that are great about the later levels is that you pretty much are a demigod and can easily break some parts of reality. I'd say levels 12 or 14 are probably caps. Implementing the higher could only feasibly be done via cutting a lot of the best things for them. The exciting spells and stuff are things that don't really translate good into a video game.
