I think it's worth the investment especially if you it regularly to produce lots of videos. It's a bit expensive for just one off videos though. The reality is that any of these video making software online programs is only worth it if you use it extensively. The advantage of Content Samurai is that there is virtually zero learning curve and you can produce a slick video slideshow in a few minutes after signing on.
This video editing software for Mac has a proven record of excellence in the many movies in which it has been used. Amongst the best known titles in a long list are: The Rules of Attraction (2002), Happy Feet (2006), The X-Files: I Want to Believe (2009), Gamer (2009), By the People: The Election of Barack Obama (2009), The Patrol (2013), and the recent Saved by Grace (2016).