The phrase "interesting observation" means noticing something that catches your attention and is worth thinking about or exploring further. Full definition
Some very interesting observations about the differences between the petitions that demonstrate how the petitions themselves are reflections of which corner they represent. (christinaepilz.com)
Again, this is a very, very interesting observation on your part, but an accurate one. (gritandglamour.com)
But there is one more interesting observation on this fund that follows later. (unovest.co)