i found it very difficult to aim with the black crosshair, but i know you fixed it already. also, having to look for the portal breaks the high speed flow of the game a bit, so if you don`t want to add a 3d beacon marker thingy an idea is to maybe add a 3d sound to it, or some sort of visual cue on the level that helps you find it.
as other anon mentioned, the projectiles look similar to monsters themselves, and I often tried to shoot them but i got used to its, so i guess its not a big deal
will try again on future builds