The Celebrity Infinity is an older ship but is maintained well and the cleaning staff are first rate.
Stateroom: we had a prime oceanview cabin. We had a super bargain rate for an inside cabin including classic drinks, wifi and onboard credit, so we took the chance and bid for an upgrade which was accepted - $160 pp. Our room was kept spotless. The furnishings were a bit worn but clean. We had family members in Aqua Class, however, who were not pleased with the cleanliness of the upholstered chairs. Also, there were big rusty stains on their balcony. I think knowing it is an older ship, you would plan on fully inspecting your room the first day and if there is something not to your liking immediately go down and change to another room before you move in.
We upgraded to the premium drink package and took full advantage, don´t forget the good coffee and all the mineral water (Evian, Acqua Panna, S. Pellegrino) is included as well! Ask your stateroom attendant to please empty your minibar and you can fill your refrig from the cafes.