I personally don't see the point of deciding to use a plus sized star such as Adele and then cropping so much into her face. It's predictable and sort of stupid. It's Adele. We all know what she looks like. We can handle more than her face and lots of hair. She's a beautiful woman and that should be shown.
All that being said at least it's a nice headshot. Before a lot of the 'boring' comments come in just be thankful it's not another horrific headshot like we've had previously. Kate Winslet's or Gwyneth's last cover for example. At least it's been done well.
To be honest though, I couldn't care less about Adele's looks or figure, gorgeous or not, its all about that great voice of hers and I'm interested in what she has to say for herself. Seems like a logical move by Vogue UK to use Adele, I think this issue will sell well.
There is going to be a lot of wank over the team choosing a close up shot instead of an image showing her "beautiful figure" but I don't see any problems with what they've done. With any iconic figure, which Adele is close to reaching at this point IMO, covers tend to be a close up shot.
And its not as if they're straying far from formula - Vogue UK does quite a lot of face only shots. I think its better that the cover is a closeup because if anything its accentuating just the person, not the figure - Adele isn't a plus-size model she's a singer.