21

21 announced Adele's voice as the defining pop instrument of its decade — a mezzo-soprano of rare power and control that reviewers consistently identified as the record's foundation. The songwriting matches it: direct, plainspoken breakup songs that build to grand, gospel-flavored climaxes without losing conversational intimacy. The production, helmed by a team of established hands, reaches back to 1960s and 1970s soul, R&B, gospel, and country, giving the record a deliberately timeless, retro-leaning warmth. The strongest songs — a stomping, vengeful opener and a bare piano closer that became a worldwide phenomenon — were hailed on release as instant standards, and the album's standing as the best-selling record of its century makes it a cultural landmark as much as a musical one.

The weaknesses critics converged on are the flip side of that ambition. Several reviewers found the album's middle section sagging, with ballads that blur together under the weight of its relentless heartbreak theme; a cover of a Cure classic was the most frequently singled-out misstep, widely heard as an unnecessary, soft-focus misfire. A minority argued that the multi-producer, committee-style assembly shows in places, smoothing the rough edges off what might otherwise have been a rougher, more idiosyncratic record.

Where critics genuinely split is on consistency and style. Nearly everyone agreed on the voice and the peaks; the dispute is whether the full 48 minutes sustain those heights or whether the sequencing lets the momentum stall, and whether the retro-soul production reads as timeless craft or as homage that occasionally tips into pastiche. Those arguments never dented the album's commercial and cultural supremacy, and the retrospective consensus — reflected in decade-end lists and all-time rankings — treats it as one of the defining pop records of its era.