Enemy Mind has an interesting concept going for it, ship-switching in Shmups hasn't been done all too often. The problem is, this hinders the game from achieving greatness. Turning it into something more resembling a puzzle game than a shmup at times.
See, you gotta switch ships constantly - because they run out of ammo quite quickly. Eventually you will be switching between the same couple of ship-types you feel are clearly better than the rest thanks to superior attack patterns covering more of the screen and higher armour-ratings allowing you to take more hits. Thus the game quickly becomes samey, with wave after wave of identical craft and similar situations all the time. Enemy Mind fails at keeping things fresh - after the first 20 waves you get the idea what this game is all about and to be honest, it is hardly worth checking the remaining 60 or so waves - even the bosses get recycled twice and it is all a bit dull.
The game also lacks punch, the basic small fighters feel almost like the ship from Defender. Somehow the entire game has a weird eighties-feel to it not unlike a couple of early homecomputer shmups. Everything is kinda small, demanding very precise shooting with beams and projectiles that most of the time are exactly one pixel in height. There is not a whole going on, which may or may not appeal to you - personally, I miss screen-filling enemies, massive explosions, gigantic lasers. Enemy Mind is wimpy at best in that regard - unfortunately the minimalistic aesthetic also becomes problematic on smaller screens (I was forced to go vintage, since the game wouldn't run on my main setup) with easy to miss projectiles and almost invisible mines.
Overall, I feel the game offered too little variation in the three hours it took me to beat the final boss - the weird story only did so much to keep me interested in playing and going for high scores is hardly entertaining and bored me quickly. Might be worth it for that limited eighties-gamefeel, but as far as shmups go I prefer the likes of Astebreed, Satazius or Crimzon Clover.