The first two-thirds of it are much funnier than the last third. Everything gets wrapped up incredibly neatly, which I suppose is the whole point, but it means there isn't a breath of air in the last pages, and you almost yearn for something to upset Flora's plans at the last minute. That said it's quite witty and clever throughout, and Stella Gibbons' sentence construction is a thing to behold: she kind of combines mid-twentieth century Muriel Spark-ish tartness with the flawless, rolling rhythm of the Victorian sentence (or something like that). I can't believe this was her first novel; it's so poised.
I did wonder why the novel is set 'in the near future' and why there's all the emphasis on flying and other kinds of technologies. Just to point up the primitiveness of Cold Comfort Farm?
I also wondered why all the emphasis on Mr. Mybug. I found his first conversation with Flora about Bramwell Bronte and his gin-swilling sisters the funniest part of the book, but it did strike me that you could remove his character completely from the book and not really make any fundamental difference to how it is constructed (apart from needing to find another husband for Rennet). I wondered was Gibbons making a certain point of contrasting the sanity and civilised values of the female author (i.e. Austen as a model for Flora to attempt to copy) with the irrationality and egotism and sex-obsessiveness of her male counterpart (Lawrence perhaps?). That's probably way over the top, but it did seem like Gibbons might have had a satirical axe to grind or perhaps somebody specific in mind in the Mybug scenes.
If you're into Mundane Literature of the Victorian kind, read on.