Bhagavadgita is a scripture written in the form of most beautiful poem. It tries to comprehend most of the philosophical concepts spread through Upanishadic literature. Moreover, it is a part of the epic Mahabharata and it is tied into the characters and stories of Mahabharata.
Full understanding of Bhagavadgita needs an extensive understanding of Mahabharata and Upanishads. Very good understanding of Bhagavadgita needs understanding of Indian Philosophy, especially the culmination of Indian Philosophy into Vedanta. Bhagavadgita can be partially understood by the ones who do not have the earlier mentioned background when they read proper translations. Some creative writers can make non related creative meaning out of Bhagavadgita. This has made Bhagavadgita most respectable scripture not only in Indian circles, but also non Indian circles! And, this includes even non philosophical circles.
Bhagavadgita is not trying to drive a single message through all its 18 chapters. Of course, the need for one to perform one’s ordained duty without getting obsessed with the results, and at the same time keeping focus on the permanent Self is predominantly stated. However, various different paths for different types of people are mentioned. It also states that all should be let to choose their own methods and continue them till they find their most desirable path.
Bhagavadgita is like a Mall where one finds multiple kinds of stores. One does not have to visit all of them or one does not have to purchase from each of them. They can visit whichever stores they want, and purchase whichever things they want. But, they should know what they came for, what they are getting, and if they do not find what they wanted, they should not get disappointed.