For most first-time visitors to Far North Queensland, yes — even a single outer-reef day is a highlight. Pick an operator that matches your comfort level: pontoon trips are easier if you are new to snorkelling, while smaller boats suit people who want less crowding.
Weather and water conditions matter, so build flexibility into your plans. If you only have one clear weather window, use it for the reef and save Kuranda or the Tablelands for the other days.