Big Chocolate's vocals are some of the best death metal vocals I've ever heard. His guttural growls put many full-time death metal vocalists to shame. I immediately fell in love with his vocals when I first heard Burning the Masses's Offspring of Time in 2010 and I have eagerly awaited any new material featuring Big Chocolate on vocals ever since. His vocal performance on Sleeper is as good as ever and it is the highlight of the album. I think Big Chocolate should do more metal-related stuff and less dubstep stuff, but that's my own personal opinion and I'm sure there are plenty of people that prefer his dubstep work.
Another aspect of Sleeper that I really enjoyed was the use of keys and ambiance, which is generally pretty unusual for brutal death metal. The keys compliment the rest of the music nicely and do not feel out of place like one might expect. This, in addition to the outstanding vocal performance, help set Sleeper apart from the rest of the brutal death metal scene.
Sleeper is an outstanding brutal death metal album that has very few flaws. As a matter of fact, the only flaw that comes to mind is the length. Clocking in at a mere twenty-one minutes, Sleeper is not very lengthy and will most likely leave fans craving more Disfiguring the Goddess material. The ferocity of the album is complimented by an incredible vocal performance and tasteful use of keys. I would recommend Sleeper to any and all. On a final note, the cover artwork is absolutely phenomenal.