Basically, yes. Intelligent non-shared-verbal-language sentient.
It did not fail the Harkness test but passed with an asterisk warning; as the asterisked section denotes, while body language is dangerous to rely upon because you could misunderstand (or manipulate a non-sentient into learned behaviour), the unicorn very obviously is sentient and reacts to words, looks, and actions in ways that shows sentience and understanding and altogether human mentality, though it cannot communicate directly through a shared verbal language.