Mathcore has one major appeal, and this is the chaotic aspect. The rhythm changes unpredictably within one song and atonal sounds are used. These seemingly wrong sounds are what makes the music especially interesting.
What still makes it music is, that it doesn't do that every second. It's still sounding fine and has lyrics like you'd expect. And depending on the song, patters of this anomalies emerge.
The only bad thing about the chaotic aspect is, that you can't really headbang to it. It's also hard to dance to the music.
Ionenbombe and I were joking around and actually found something by inventing 'slizing'. You simply slide your feet around fast on a moderately slippery underground, not moving much out of your place and hold balance.
In addition, you can also wiggle around with your chest.
We found this rather exhausting, but still fun. Especially the chest-wiggling is harder on your muscles and you need to pay even more attention to not fall.
The word is a combination of 'dancing' and 'sliding'. To not confuse it with 'slicing', we replaced the 'c' with a 'z', which also makes the word sound better :P
Going back to the music-genre: The second aspect is, that it's hard. You know, fast drums, shouting, mainly growling and screams, this kinda stuff.
While I listen to a wide variety of genres, metal is one of my favorite. I don't know why I like it, maybe it's just its aggressive nature, but it somehow appeals to me.
Just as well I like slow and emotional songs though, but chaotic rhythms simply don't fit too well in there :P