This book started out a little slow for me, as it spent a lot of time talking about "primitive" computer dating, which started as far back as the 1960s when a program would match up college students in Massachusetts. My interest picked up as it entered the realm of Internet dating as I know it -- and as I experienced. It also goes into the realm of forms of online dating that are still somewhat stigmatized, such as "mail-order brides" (dating sites that focus on matching women in the developing world with American men) and sites specifically to facilitate affairs (yuck).
One of the things I found most interesting was the fact that for many people, Internet dating has given them a sense of "abundance" -- whereas once people might have tried to "work things out" because they were under the impression that finding a new partner would be difficult, now it's supposedly easier for people to get out of lackluster relationships and to get over it more quickly by jumping right back into the market.
Somewhat disheartening was the cynicism of the teams behind most of these dating sites. Many of them do not believe they are facilitating permanent relationships -- they buy in to the idea that it's easier to find a mate and so sustaining a long-term relationship is less likely, and perhaps not even desirable. Because of course, once people pair off permanently, they have no more need for the dating site -- so it's not actually in exec's best interest for the sites to be truly "successful" in matching people up.
Like many books of this nature, this one skirts toward the alarmist at times: online dating makes people too picky, makes it too easy for them to be dishonest, makes it too easy for folks to leave relationships or be unfaithful, etc. This was not really my experience -- it was pretty easy to weed out the folks who were jerks, not serious, or otherwise "undesirable" before a first meeting ever took place, and everyone I ended up dating IRL was more-or-less who they presented themselves to be. And now that I am coupled off, I still have a healthy fear of how "hard" it is to find another worthwhile partner and thus invested in the one I have.
I think online dating, like other social media, exaggerates people's natural tendencies, or makes it easier to act on the less socially acceptable inclinations people have. But I don't think it can "make" someone who would have been a good partner in the past (i.e.: pre-online dating) a lousy partner in the present. Online dating, just like meeting people IRL, requires a certain level of discernment and self-awareness, and those who lack those characteristics are going to have a more difficult time of it.
It was interesting to learn more about OKCupid's demographics, which was the dating site I used. I opted for it for two reasons, both of which were very important to me: 1) it was free and 2) it allowed users to select "bisexual" as an orientation and search both men and women. But it turns out I pretty much matched OKC's demographics in other ways, too, as the book described it as appealing to the "geeky, writer types." No wonder I met the love of my life there! (This book also pretty much convinced me that the folks behind Match are all a bunch of crooks.)
So: I think people without personal experience with online dating would find this book alarming and might wring their hands over what the young folks were doin' these days. I think those with personal experience will recognize their experiences in some places and be shaking their heads in others. All in all though, it's an interesting look at something that has become standard fare in the dating world, and that is definitely here to stay.