With Instagram you have a whole new way to tell a story - through images. So it is important to do so. You want to make your brand stands out and you want people to connect with your company on a human level.
By adding both fun (or personal) photos as well as business photos, you are going to be able to do this. But again, there must be some type of connection between the images so that the visitor is going to be able to put the story together in the end. If you are simply adding images on a random basis or throw in images that are not connected in some way, it is going to take away from your story.