Doctor Dolittle is a strong option for learners who already feel comfortable with English and want a more demanding challenge. Some conversations move quickly, so learners may need to listen to certain parts more than once at first. The language mixes everyday English with a few expressions that need attention, so it works best for learners who already have a solid base. Also, jokes, quick reactions and casual exchanges are a regular part of the dialogue. The story gives enough context to follow what is happening easily. If your English is close to B1/B2, Doctor Dolittle can be useful for getting used to faster spoken English.