Quite the workout! Both fights with Metal Sonic and The Great Robot were quite difficult, forcing the player to choose their next moves wisely. Tails is equipped with limited offensive spells, making the fight a bit troublesome. However, besides that, he can analyze the two to level the playing field by discovering weak points. An amazing game, although more can be added to it's cutscenes though.
To those of you having trouble with the last fight, the trick is to hit the robot in it's "sweet spot". Tails' Scan ability even tells you that. Pepper him with Triple Shot and never lay a finger on your MP skills or Giga Beam, ever, except Healer. When your health is low after taking in The Great Robot's giant beam, heal. Pepper him with Triple Shot when "sweet spot" is exposed, heal after it closes up. Shoot him with energy bursts. Repeat.
A fun game to pass the time, indeed.