[2] Merat further noted that the band made a conscious decision with Vermis to bring back "a level of unpredictability we've always had in the past" due to the feeling that the previous album, The Destroyers of All, "came out a little too fluid on the whole".

[5] According to Merat, Vermis uses the metaphor of invertebrate animal species to explore "the over-arching theme of spinelessness [and] oppression".

Several reviewers noted that Ulcerate's approach posed a challenge for casual listeners, with Greg Pratt, Dave Schalek, and Brandon Ringo cautioning that Vermis placed exceptional demands upon its audience prior to disclosing its positive features.

[8] Praising the band's "distinctive voice", Popmatters' Craig Hayes observed that Vermis extended the band's "continually refined" creative trajectory by "bringing more artful sculpturing to its downtuned dissonance and complex time signatures, and setting that against a backdrop of often droning and industrial textures.

The band’s work has evolved to become steadily more nerve-shredding and formidable, with the usual riff-based shreds of death metal mutilated into a seething and polychromatic canvas of avant-garde atmospherics".