Expect a fast ride to the 89th floor in one of the world's fastest elevators, then solid 360-degree views of Taipei's sprawl, distant mountains, and the city grid. The deck is clean, modern, and fairly spacious with big windows, some outdoor terraces when weather allows, and decent info panels. It's touristy but efficient; most people spend 30-60 minutes unless they linger in the gift shops or café on the floor below. Crowds can feel busy on weekends and holidays, but it rarely feels overwhelming.
The best time is late afternoon through sunset, especially on clear days. Avoid midday haze in summer. Spring and autumn usually give the best combination of weather and light. Expect to pay around NT$600-850 per adult including the basic observatory ticket; add a bit more if you want the audio guide or a combo with other building attractions. Kids and seniors get discounts.
Pick a clear day or go for the sunset slot if you can time it. Skip the overpriced themed exhibits on lower floors and the long lines for the damper if you're short on time. If you're into tall buildings or want a reliable city overview on a first visit, it's a solid pick. If you're on a tight budget or have already done similar decks elsewhere, you can skip it without much regret.