If you are familiar with the recommendation tools by companies like Disqus, Taboola, and MGID, Google's Matched Content works the same way but there's a huge difference. Taboola and MGID curates content from its member websites so pages from these websites are the ones that appear in the recommendation tool. This is because their business models rely purely on their member sites. Google's Matched Content is different because it's a pure recommendation tool for the website or blog that installs it. All the pages and links that the tool recommends are pages from the website. This is unless you opt to include Adsense ads to appear on the tool.
Anyway, as I mentioned above, I tried Matched Content for several months and here are my observations. One, it's really effective in introducing the visitor to more pages in your website. When I looked into the statistics for my website, I saw a significant increase in the amount of time that visitors spend on my site especially for new readers. This means that the Matched Content tool is encouraging visitors to read more posts in my website. Posts that I wrote months and even years ago are now getting trickles of readers because of the recommendation tool. That said, as far as recommending is concerned, Matched Content is quite good with it.
How about if you opt to include Adsense ads among the links and pages shown in the Matched Content tool? Before I tested this option, I was expecting to see an increase in my Adsense earnings. Unfortunately, there was no effect at all. After months of using the option, I didn't see any significant increase in my earnings because of the ads inside the Matched Content feature. Of course, I'm getting steady clicks on the ads but nothing really special. I could've used a standard Adsense unit in place of the Matched Content feature and I surely would've made more money. In short, don't bother activating the ads in your Matched Content tool. If you're going to use the tool, use it purely for its recommendation capabilities.
Although I liked the recommendation tool, I still have my reservations. I do believe that people will start ignoring the recommended articles because they look too similar with the spammy links and stories that other recommendation tools are using out there. I'm hoping that Google would do something to differentiate their tool from the others.
In conclusion, is it worth it adding Matched Content units on your website or blog? I'd say it's worth a try. Just give it a shot, track your statistics, and see how it performs. Who knows, you might get better results than I did.