This one really is a waste
Now, Xevious is a game where you fly a plane and have to shoot down enemies with one button while bombing ground targets with another button. Both flying and ground bound targets can shoot at you, so you also have to avoid being hit. The farther you reach the tougher the enemies etc, and the challenge is to pay attention to both ground enemies and flying enemies and to divide your attention between attacking and dodging. It is quite challenging and I can understand why this was considered a great game back in the day – particularly the arcade version, but the 3DS version simply doesn't work as well – and it is all because of the graphics.
Now, the only thing 3D does is to make it so that there is a foreground – the sky – and a background – the ground. Rather than adding to the experience, this just makes the game uneasy on the eyes, particularly with the many small particles that are flying over the screen in the foreground, so that is an absolute fail. I doubt there is a single person who would say the game is better with the 3D effects turned on.
However, 3D can be turned off, so the biggest problem for me is the 2D graphics. It is important to remember that the original game was supposed to be played at a television screen. While TV screens back in the NES days were not the size that they are today, they were still considerably larger than the screen of a 3DS – and that is what causes the problems. You see, while the glowing orbs that the enemies try to shoot at you were easy to spot and avoid in the original (I would assume, I haven't played it), in the 3DS version they are really tiny. While this isn't a problem to begin with, it is a huge problem when there are several enemies shooting at you. Ninety percent of the times I die it is because of a shot I simply didn't see.
So there you have it. The 3D version of Xevious is simply a waste of your time and the little money it costs and you really shouldn't bother with it.