We loved Cafe Mickey and so did the children. Its a middle of the range Character Meal. Inventions is more expensive and Cowboy Cookout is cheaper.
We will always have one meal here per trip because we feel thats where we get our character interaction.
In regards to whether to book, it depends if you are going at high season, are flexible with the time you are offered and how large your party. We've never had a problem getting in during quieter times (early June/early Dec) but by the time we leave have seen long lines of people waiting outside.
We are going next week and have decided to eat there twice, with a 19 month old requiring food earlyish we decided to book all our meals, Im not taking the risk in high summer.