This was our 3rd cruise on Carnival (previous ships were the Paradise and Breeze). It was also our last, I will cruise Royal Caribbean from now on.
Maybe if you've never been on a cruise before, you wouldn't be completely disappointed, but if you've been on any other half way decent ship (the Breeze was very nice), you will not be happy with the Sunshine.
A few positives - the Cruise Director, George was awesome. Our room steward was very friendly. The three level Serenity deck was what sold us on this ship and what we looked forward to the most. It was very nice, however always too crowded and the pool is too small for the amount of people that frequented that area. It was closed one day because some idiot threw up in the pool, although that wasn't Carnival's fault. I did love having a balcony too.