Landry is a big unknown to the majority of moviegoers. You Friday Night Lights fans might recognize him (that show is becoming a go-to for mutants) but he's probably best known as being "that kid on a bike" from the end of No Country for Old Men. That probably qualifies him to fight anything mutant haters can throw at someone. If you talk to Anton Chigurh and survive, then what else is there?
So, that's the actor. What about the character? Well, Banshee was an Irish mutant who possesses the power of a sonic scream that can cripple enemies. (I'm guessing the Irish angle will be dropped since Landry is a Texan.) He joined the X-Men the same time as Wolverine. Despite a lilting accent and a similar pair of muttonchops, he didn't go on to appear on multiple superhero teams or land his own Hugh Jackman-led franchise. Perhaps his luck will change with First Class. But wouldn't it have been cool to see Cillian Murphy play this back in the early heady days of X-Men?