I have sailed on the Poesia, but in the Mediterranean rather than the Caribbean.
It is a sister ship to the Orchestra, that is, exactly the same in size & layout etc..except that the speciality restaurant is sushi rather than chinese. You will not find any reviews of the Poesia in the Caribbean as it was only launched in April 2008, and has not yet been in Caribbean waters.
MSC has had ships in the Caribbean for a few years now, but the passenger base has been predominantly European. With the arrival of the Orchestra, it seems their ships are now being actively marketed in the US. As a result, it seems the ship's are being monitored and a few minor changes may be introduced during this season. My advice to you is to keep checking the reviews for the Orchestra to see how things are going.
If you have any specific questions about the Poesia, I'll be happy to answer them.