This was our (age 30/26) first cruise so needless to say that we were excited and enjoyed our trip with Celebrity. I cannot provide comparisons with other cruise lines but will provide our experience on Infinity.
We had perfect weather in all ports and at hubbard - not a single drop of rain - we were prepared for rain because of the time of our trip - but we were lucky !
Ship: Infinity is a well maintained ship and public areas may show some wear (especially on carpets) but nothing that stands out. We saw HAL and RCCL ships on other ports and Infinity seemed better exteriorly.