First and foremost, certain bubbles in Puzzle Bobble VS are virtually indistinguishable from one another. Blue, dark green, purple, and black bubbles are only separated after much eye straining and squinting. What is the point in playing a game where the goal is to match up bubbles of the same color if you can't tell them apart?
Puzzle Bobble VS second flaw is its maddeningly slow pace. Maybe the intention was to slow gameplay down just enough to give players time to labor over distinguishing colors. Puzzle Bobble was meant to be played as fast as the player could think, but with Puzzle Bobble VS the game moves so slow that by the time the bubble reaches its target and a new one is loaded, you would have wasted the time you should have used to load another game into your N-Gage.
The one redeeming quality in Puzzle Bobble VS is, you guessed it, the versus mode. Gameplay doesn't magically improve, and the bubble colors don't suddenly take on a higher contrast, but you can challenge a friend to a slow and methodical versus match. Again this only applies if you have super human vision and timeless patience.