Thanks, prospero, for saving me the trouble by putting so eloquently into words the thoughts that I was formulating. I would add that (and I think it’s implicit in what you have written) I cannot see that there is anything ‘unfair’ about this crossword. As you and others have demonstrated, there are several possible ways of tackling it, all requiring a modest amount of lateral thinking (which adds a bit of spice to the exercise). Very few of the non-12 have antonyms, so that immediately narrows the field considerably.
Before the Maskarade special just before Christmas, I was concerned that the Guardian Prize was becoming too easy (often much easier than some of the weekday offerings), so I’m pleased to have been presented with slightly more challenging fare over the last three weeks (though I can see why many might have felt that the Maskarade was a shock too far - I enjoyed it but the theme was very much to my taste). In fact last week’s jigsaw was still a lot more straightforward than still-lamented Araucaria’s.
If there is any criticism to be levelled at all, I suppose it might be of the crossword editor’s decision to run three ‘specials’ in a row. Brummie can’t be blamed for that, however, and I do think it a shame that his hard work should be greeted with such negativity.