Chris Campbell’s review published on Letterboxd :
The first remarkable thing about Inside Out was that it was made. Pitching an idea for a film that is a visualization of emotions and how we deal with them doesn't seem really obvious as something that will work, but it does. Pushing the boundaries of animation in terms of themes and techniques is something that Pixar can do really well and Inside Out surprised and delighted me. Visually it's beautiful with a complex and coherent metaphorical construct of how feelings develop and influence how we behave and within that structure there are interesting characters and a story that I really cared about. Much of the joy and pleasure of the film is the revelation of more details about the inner world as it progresses, so I am glad that I saw it early and without reading reviews. It's also a film that has stayed with me for days which is a very good thing.