Generally, I can't stand all these post-hardcore bands. They all sound the same to me - Asking Alexandria, Miss May I, Alesana, etc. Of Mice & Men is one of the post-hardcore bands that I actually like. The album instrumentally isn't that great. It really isn't different than most 'screamo' bands; the guitar's repetitive chugging, the drum's straightforward riffs, the only thing that makes OM&M stick out to me compared to other P-HC bands is the singer. The way the two singers [Shayley does cleans, Austin from "Attack! Attack!" did screams on the album after leaving AA, and after the album got heart surgery and could no longer perform, in which they brought in their current screamer, Jerry, as a temporary replacement, until Austin quit] both sing and scream is different than other bands, and it's great. It's on songs like "Second and Sebring" and "Farewell To Shady Glade" where you can't get this band mixed up with the other generic sounding bands.
Also, with Of Mice & Men, the guitar is on a higher scale. Instead of that Drop-C tuning you'll hear quite a bit, it sounds as if it's in Drop-D, and even with that, they still play higher. It gives things a nice change. The songs are strangely catchy, and I've listened to the album a few times, but they also don't seem to have much organization to them. All in all, Of Mice & Men's self-titled is a good album, and I hope to hear more from the band soon.
[Thanks to Alex Hunt, my best friend ever, for the information on the singers :D ]