'The plot was great but it was just too difficult of a read to carry on.'
'Basically a copy and paste of other werewolf romances, FML!'
'Must ... complete ...'
'My daydreams have not benefitted from this at all.'
'How the @#%^ was this even given even three stars!'
Every one of these thoughts has led to a book being placed up on the dreaded 'waste of money' shelf (in the case of Epeolatry London, it is our 'waste of a tree' shelf); whether figuratively or literally. They are rare, but they are still out there and every now and then they slip through our fiercely guarded blockades and you are left with a book that you cannot even bare to give away for free.
The creative may create something magical out of them, but the rest of us will be left with one less book space. And what will rankle us the most about this - the fact we bought it based on a review or recommendation. Book reviews may be personal (as they are based on how the reviewer reacted to the narrative) but there is more to a book than the plot.
(Allegory time!) A baker follows a recipe up-to a point and then start to do their own thing. That is fine as long as the basics are there - flour, water, egg and yeast. The end result may not be to your taste but to someone it is. This is the same with books. But should they forget the basics then everyone will struggle (to differing degrees) with its' consumption. And this is the reason that no great plot can make up for a complicated or poor style (we have read and given up on enough to know that); just as how a magical world can create an environment for unrealistic events (praise to G. R. R. Martin for showing how it should be done).
We are not focussed on whether we enjoyed the book - although the reviewer's opinion will be given in a separate part of the review - but the readability, skill and style that lays the foundations on which you will walk into your next journey with words.
One last thing ...