Was a bit wary of Celebrity, and Constellation after reading many previous reviews. This is my experience:
Embarkation from Venice was a complete shambles, with no supervision of the check in queue. You are assigned a letter which is called, then you queue up. No. Didn't matter which letter was in progress, everyone tried to get through. First impressions were i am not doing this again, on any cruise.
Once aboard, (after approx 2 hours) we were greeted with a glass of champagne, or fruit juice, then off to Oceanview for a meal. Food here is average, not great, certainly not up to the standard of Royal Caribbean.
Cabin more than adequate, plenty of storage, large comfortable bed. Good shower with curtain. Always kept clean. Balcony small with two chairs. Good position for views.