It's not that bad, and it depends on the difficulty level you were playing on. Stage 3 is bullshit due to pits/small ledges but as long as you adequately dodge and use your upgraded skills appropriately you won't have that much trouble. Some people complain that your shield is also your skill-bar, but you need to balance between exhausting that bar and clearing out loads of enemies so that you don't take hits in the first place.
I hardly ever see anyone mention or even remember that each character is based on a classic game moveset, the bunny being Metal Slug or Milia being Kirby.