Gizmodo has a great article up a video done by Youtuber kaptainkristian detailing the reasons Who Framed Roger Rabbit worked so well.
From the site:
Robert Zemeckis has been hit or miss for almost two decades. But in the eighties, he was on fire. Along with Back to the Future, Who Framed Roger Rabbit is just one of those movies that remains great no matter how many years pass and its technical achievements are still a marvel. But why does it work so well?
From a storytelling perspective, Roger Rabbit was funny, unique and had some great performances from people like Bob Hoskins and Christopher Lloyd. But YouTuber, kaptainkristian is more interested in breaking down what sets the film apart from other movies that try to mix live-action with animation.
Check out the entire article here.