The farmhouse itself no longer looked like a beast about to spring. (Not that it ever had, to her, for she was not in the habit of thinking that things looked exactly like other things which were as different from them in appearance as it was possible to be.) But it had looked dirty and miserable and depressing, and when Mr Mybug had once remarked that it looked like a beast about to spring, Flora had simply not had the heart to contradict him.
Gibbons then goes on to describe what the farmhouse does look like.
It looked dirty and miserable and depressing no longer. Its windows flung back the gold of the sunset. The yard was swept clean of straws and paper. Check curtains hung crisply at most of the windows, and someone (as a matter of fact it was Ezra, who had a secret yen for horticulture) had been digging and trimming up the garden, and there were already rows of beans in red flower.
'I,' thought Flora, simply, as she leant forward in the buggy and surveyed the scene, 'did all that with my little hatchet.' And a feeling of joy and content opened inside her like a flower.
Of course in that second paragraph, Gibbons is using both metaphor (there was no actual axe involved!) and simile (joy opening like a flower), which seems to contradict what she had just said, but whether it was done consciously or unconsciously, I don't know, but she seems to be showing that, like everything in writing, metaphors and similes can be used well or badly. Though the 'flower' simile might not be utterly original, it is simple and it is being used to describe something that is, otherwise, very difficult to describe effectively (namely a feeling) whereas describing the house as being like a 'beast about to spring' is laying atmosphere on with a trowel.
As is always the case when talking about description, looking at one instance may seem OK, but Gibbons was having a dig at the writers who think if one simile makes a passage more vivid, ten must make it ten times as vivid, which most certainly isn't the case.
For anyone who struggles with description, it might possibly help to look at her deliberately overwritten passages, which she has helpfully marked throughout the book with three stars *** to show the reader how 'wonderful' they are. Sometimes seeing something completely overdone can show you how to do it well by doing what that writer has done but just dialling down the volume from 11 to about 4. :)
[*] Diana Wynne Jones wrote The Tough Guide to Fantasyland in which she mercilessly sent up a certain type of fantasy. She also wrote The Year of the Griffin, in which she took all the clichés and made them work in a book that was both funny and moving. But very wisely, she didn't try to do both in the same book.