My overall impression from years of reading them is that if you look at only “helpful” reviews you will filter out negative ones disproportionately to their actual helpfulness, presumably because of a human tendency to dislike negativity. One workaround is to look at, say 3-star reviews (these tend to list both pros and cons) and sort just the three star reviews by helpfulness. There are other workarounds. The first thing I usually do is sort by “newest first” and skim a couple of pages of those. Edit: but checking the Amazon page, there are only 23 reviews in all for that particular book, so, you can just read all of them, which you seem to have done.
My overall impression from years of reading them is that if you look at only “helpful” reviews you will filter out negative ones disproportionately to their actual helpfulness, presumably because of a human tendency to dislike negativity. One workaround is to look at, say 3-star reviews (these tend to list both pros and cons) and sort just the three star reviews by helpfulness. There are other workarounds. The first thing I usually do is sort by “newest first” and skim a couple of pages of those. Edit: but checking the Amazon page, there are only 23 reviews in all for that particular book, so, you can just read all of them, which you seem to have done.