The Seaside is a beautiful ship. There are a lot of polished - and even upscale - touches that *should* make it an excellent experience. Somehow, these touches don't quite add up to a great week. It's hard to say exactly what's wrong with the Seaside, but it's clear that MSC doesn't have it figured out for American sailings yet.
Since MSC is unfamiliar to many Americans, it would be a good question to ask which more-familiar American cruise line is most like MSC. It's a difficult question to answer.
Let's start with the good: the water pressure and consistently hot water in the shower are the best at sea. The Spa is large and the Thermal Area is large (and interesting), too. MSC requires you to book not just a cabin but also an "experience." We chose the Aurea experience, which included a massage. It also included access to the Thermal Area all week. There was a snow room! That was unique and fun.