Hugh - and others - thanks for the comments. My slight disappointment wasn't caused solely by that puzzle being too simple - it was partly because I'd never had any disappointing puzzles from Vismut! I've always admired her work, her ingenuity etc - and just felt a little short-changed. It was a bit like going to your favourite restaurant, where you've had some fantastic dishes, and having a meal that was ... just OK.
There are other regular setters who often feature simpler puzzles and I am quite happy for those to encourage new solvers (even if I don't enjoy them much myself!). I think this was the first 'simple' Vismut I'd encountered, and I have no qualms about not being a fan of it!