This sentence has nuance because:
* It expresses both appreciation and concern: It acknowledges the speaker's positive feelings about the plan while also expressing a cautious reservation.
* It implies a potential problem without directly stating it: Instead of directly criticizing the plan, the speaker hints at a potential issue ("overly ambitious," "unforeseen complications").
* It leaves room for interpretation: The listener must infer the speaker's precise level of concern and the nature of the potential problems.
Nuance is about expressing complex ideas and emotions in a subtle and layered way, often leaving room for multiple interpretations.