The 2007 version of Mayhem is as grim as ever, and Ordo Ad Chao is an outstanding black metal album. The production is sparse and low-fi,with a lot of treble and not much bass. The songs are evil and disturbing in true Mayhem fashion, and once your ears adjust to the production style it's even better.
The album is very atmospheric, but there are also some interesting riffs that catch your ear. The star of Ordo Ad Chao is Hellhammer. His drumming is simply crushing. Attila's vocals are harsh and demonic, and his return has improved the band's sound. Mayhem helped define a genre of music, and there's always the concern that a veteran band just doesn't have it any more. That's not the case with Mayhem, who continue to define black metal with another memorable album.