I booked my tickets in advance through the app (135k VND/adult ticket). I carefully called the hotline to ask for necessary information before going to the ticket exchange location. The staff directed me to the 19/8 Flower Garden (near the Grand Theatre) to exchange my tickets 15 minutes before the bus departed. I chose the 6 PM trip, but arrived at 5:40 PM, and the ticket booth staff said I had to wait for the next trip (7 PM) because it was full and all buses were gone. While waiting, near the flower garden, I only saw one bun cha (grilled pork with vermicelli) restaurant. I went in to eat, but the food was terrible: bun cha 50k VND/serving, spring rolls 13k VND/piece, iced tea 10k VND/cup. The owner was enthusiastic, though. After eating bun cha, I went to Matinee Cafe right next to the bun cha restaurant; salted coffee 60k VND/cup, matcha latte 80k VND/cup. I waited until 6:30 PM to be sure I could get on the bus. We boarded the bus on the second floor. The staff didn't provide audio guides (the reason given was that they weren't available on the night tour; only daytime tours had them). The bus departed from the Opera House at 7:50 PM, traveled along various streets, and returned to the starting point (approximately 60 minutes). Overall, it's only worth trying once; nothing particularly special!