My experience is kind of half-good and half-bad. I was on the MSC Fantasia, middle east trip and I think 99% of my enjoyment aboard the ship was because of the room I was in (+the benefits me and my family got with it).
First day was awesome just to see the ship, walk around the mall inside it and check out everything. Was hard to believe I'm inside a moving ship lol. Pools were too packed for me to enjoy, but the room I was in had access to a smaller pool + jaquzzis which were empty most of the time, so I got to enjoy that.
The food was awesome in every resturant or place with food, but careful not to eat too much. It might be just me, but my stomach was more sensetive on sea and lets say I learned that the hard way xD
To be honest, if not for the special access I had and the big room+balcony, for me it would've been a nightmare (it was a week's cruise so maybe also because of that). I mostly enjoyed the parts on land LOL.
If your cruise is a week or less then I bet you'll be fine. When you're there you should go to some high deck or someplace high outside at night.....Pretty awesome feeling to see the ship, with all of the lights and stuff, in the middle of the pitch black sea.....Somewhat scary and awesome at the same time =P