NCTH is definitely their most mature release yet, but it's a great album nonetheless. Soupy's lyrical ability only gets better with each album. You can definitely tell they gave it everything they had on it. I wouldn't necessarily say its their best album, it could have ended much better than it did, but I still love it for what it is.
I don't really like NCTH right now, makes me feel all sad. Maybe I'll give it a shot someday else. They were pointing in that direction with the last two works, but this one really makes you feel fucked up