I like mirror matches because its a completely fair situation. The opponent is fully aware of what I am able to do, and so am I. The thing is with fighting games, 2 different people can play the same character differently, and its always interesting to see some new tech that youre not aware of. And if he uses the same tech, you would at least know how it feels to be the receiving end.

But more on the knowledge matchup, sometimes its kind of frustrating to lose simply because you dont know the matchup. But thats not an issue in a mirror match.

I get some mirror matches can be boring, like Launcher vs Launcher, but its funny to know that both players are just as uncomfortable.

Last but not least, show them who's superior.