I received 3 months for free when i bought my PS4 so I didn't see any reason to NOT do it. Now I find myself renewing my membership because it costs something absurdly low like $3 a month (I don't remember how much, but it was very low.) I don't use a great deal of the features in here but I personally can still justify the cost. It should be obvious why.
I rarely play online games because I'm not actually good enough to be part of a great deal of what goes on there. I am not really a fan of getting my ass handed to my by a 12 year old in a first-person-shooter or being derided by the same individuals who don't have jobs who are as mean as they are ever going to be in their lives (I was my meanest between the ages of maybe 12-17 years of age.)
So I don't play online games unless it is a friend or family member. I have never joined a public gaming area and I have no intention of ever doing so. So why do I pay to be part of the PlayStation Plus program?
Every month the network has 2 free games that you can download and own forevermore. It should be quite obvious that these games are not going to be the "latest and greatest" and in some months the games you are given are titles that have their new version coming out the following month. It should be evident why they would use this strategy.
Sometimes the games you are given can be a bit disappointing. For example: This month my two free games were a game I already own (Detroit: Become Human) and a pixelated platformer that absolutely sucks called Aegis.
So I groaned a little bit when this happened and then just accepted the fact that this months games are very unlikely to be useful to me. Then I just think about the fact that it cost me $3 to get to that point. I have now been a member of PlayStation Plus for 4 months and I have received 3 or 4 games for free that I actually enjoyed. Let's imagine that I actually paid for the first 3 months (I did not) but then my total investment would have been $12.
What remains of Edith Finch was one of the first free games that I downloaded and it is one of the most amazing games I have ever played. Therefore, I can conclusively say that yes, the Playstation Plus membership is definitely worth the $3 a month that you pay for it and I will likely remain a member is perpetuity.