Celebrity Millennium receives high praise for its exceptional service, friendly staff, and memorable itineraries, especially in Alaska and Asia. Guests consistently highlight the crew's attentiveness and professionalism, as well as the quality of food in the main dining room. However, some reviews note that the ship is showing its age, with maintenance issues and outdated accommodations mentioned. Entertainment and activities are generally enjoyed, though some guests found them lacking compared to newer ships. Internet connectivity and specialty dining received mixed feedback. Overall, the cruise offers great value and a comfortable, enjoyable experience, but could benefit from updates and improvements in certain areas.