There was a lot of time and effort put in to this movie and is always the case for live action animation but at least in this case it paid off winning them four academy awards(1988).
Bed Knobs and Broom Sticks also won an academy award for best special effects (1971). And for the time they were very good special effects but its clear when you watch the movie the actors were not given a point of reference to look at when working opposite animation. They seem to be looking through the character rather than at it, which is the effect that Roger Rabbit tried and succeeded in avoiding. Also the animation though prominently featured in the poster was only about fifteen minutes of this very very long movie. An other difference with this movie is that the live action actors were dropped in to a world of animation instead of the opposite, which at the time was easier. There was an un spoken rule in animation that you never move the camera and they kept to the rule with this movie.
One live action animation movie that has been given a hard time is Looney Toons Back in Action. This movie if you ignore the somewhat cheesy plot is a really well made movie especially if you look at the animation. They use many of the techniques pioneered in Roger Rabbit like the way they shaded the toons and the way they blocked the scene with dummies. Brendan Fraser was much better at eye lines and interacting with the toons than Jenna Elfman his costar but she did a decent job. The key about having animated characters is for them interacting with the world around them to be subtle like you wouldn't think about a chair spinning slightly because Dafy Duck got on it because thats normally how a chair would react. This movie was really well made and is really funny with lots of great references that you don't get the first time you watch it. I feel sorry for the animators that and film makers that put so much time in to this movie.
It is obvious that live action animation has grown a lot but I think that to this day Roger Rabbit is still the one that got it right, because even thought it took an extremely long time there methods worked and will work for every other movie that uses them.