I am a solo traveler and have been on many cruises: after shopping around, I have become a Celebrity loyalist. I will only cruise with Celebrity Cruises: they treat me very well and they are the best in the business for mid-size luxury cruising.
That said, I rated this trip as "very good" (not "excellent") because of some extenuating circumstances that reflect the overall experience, not Celebrity Cruises specifically.
Getting to Auckland, New Zealand is an investment in time and funds. Plan on three days to get there if you are traveling from the east coast of the USA. Fortunately I used miles for my flights and was able to go business class the whole way. This makes a big difference, and I arrived in pretty good shape. Hit the ground running when you get there: this will help alleviate jet lag.
Avoid the Sky Suites on deck 12! The noise from the Ocean View Café above is really bad. Occasionally I smelled cigarette smoke from the smoking section above, but that was inconsequential to the terrible noise. Sounded like a heard of buffalo running overhead. Hard to get a good night's sleep. Also, the little couch is a pull-out bed. So it was very uncomfortable to sit on for any length of time. The balcony is totally covered by the deck above, so the sun never hits the space. Better off on deck 11 or lower.