Is Santorini worth visiting? Yes, once, under specific conditions. Outside those conditions you are funding one of the most efficiently commercialised tourism operations in the Mediterranean.
The caldera is real. The light on the white buildings in the morning is genuinely extraordinary. The volcanic geology is among the most dramatic in the world and worth understanding before you arrive, not just as backdrop. These are the reasons to go.
The best time to visit Santorini is May or October. Spring brings the island back to something resembling itself: the restaurants are open, the paths are walkable, and the caldera view from Imerovigli in the early morning does not require negotiating with a tripod. In July and August, the island is overshadowed by the volume of tourism it has accepted to the point where the experience has become largely transactional.
Stay in Imerovigli, not Oia. The caldera view is comparable. The crowd is not.
Skip the volcano tour. The two-day itinerary is the right frame: arrive, see the caldera villages, eat well, leave. Anyone telling you Santorini requires more than three nights is on commission.
The wine is genuinely excellent. Assyrtiko from the volcanic soil is worth the trip on its own terms.