Is Nikko worth the trip from Tokyo?
Nikko is worth it if temples, forest and a deeper historical mood appeal. It is a long day from Tokyo, so go because you want that atmosphere, not because every famous day trip belongs in the plan.
Answer
Nikko gives a different register from Tokyo: ornate shrines, dark trees, mountain air and a sense of historical weight that feels far from the city even when done as a day trip. It can be one of the better Tokyo extensions for travellers who want culture and landscape together. The catch is the length and energy of the day. If you already have Kyoto, Nara and several temple-heavy plans, Nikko may blur rather than sharpen the trip. Consider it when you have enough Tokyo time, or when that forested mood is exactly what the itinerary is missing.