The main problem I have with this game is that archers need to target the flying demons first. However, most maps allow you to place the knights/tors at an early choke point, which frees up the back to place archers. With a few patches to fix items like targeting, specifying damage levels of units and ability to send waves early this game could be 5/5. As it is, the current 3.75 rating seems about right.
Of course but not all bugs are always found. That is why we value user feedback on our free to play games. Thanks for pointing that bug out.