I think the main issue with yours controls compared to others is that people in left-to-right reading countries perceive up and right as "up" and not up and left (i could have sworn there is a Poynter institute article describing this, but I cannot find it), and this makes the number of errors go up a bit. Scott Klemmer calls this category of UX problems a "mapping issue". In the old times where 3d camera was not a choice, game devs often solved this by making sure there is a clear "face" and "tail" to the character you are moving, and that the "face" always faces up, but I would suggest you try to solve the issues and at least try mouse control (having ground as a separate layer and raycasting only against that, with highliting tiles on hover will help, if not solve the issue).
It is not a game-breaking issue, don't get me wrong, just something that made me make a couple of mistakes, so my daily job as a UX consultant started creeping in the conversation. Great game and a very nice effort.