Episode Shadow is crazy short. I finished this in 20 minutes and when I finished the third level I was shocked that's all there was. Other than its short runtime I think this dlc is pretty decent, but I may be a little biased because shadow is my favourite sonic character. The story in this ties in fine enough to the main game and my biggest issue with it is probably infinites backstory. Shadow literally insulted him ONCE which made him become an evil supervillian who wants to destroy the world. I definitely think they could have made up a better origin story but other than that I would say this dlc is worth your time.