Our family of 4, (son 12,daughter 10) really loved the ship. We previously had sailed Carnival, Royal Caribbean, and Norwegian. We had loved the Escape, but all agreed that we preferred the Seaside. The ship IS different...and that isn't a bad thing in our opinion. But if you want it to be like Carnival or Norwegian...then you probably should book Carnival or Norwegian. What I might consider a Pro, might be a Con to others as it differs from their preferences.
We had room 10212 Aurea Suite with whirlpool.
1 very important difference with MSC compared to other lines, is the "experiences". You are not just paying for a better room, you are paying for better services throughout the cruise. Higher level experiences have better dining times or dining rooms(or do not have set times), may have priority boarding, or access to certain areas of the ship. This differs from most other lines, where once you leave your room you are the "same" as everyone else. Again, this is a Pro/Con depending on your point of view. I really liked the Aurea deck, and was glad they checked everyone's card/wristband for access.
Spacious cabin. Sofa that turned into bunk bed was big space saver, and kids loved it. Large walk-in closet. Hot tub on balcony was nice bonus.