I didn't go on this cruise for the itinerary--I went for the ship. In fact, I only got off the ship once the whole time. It's really an amazing ship to behold, overall, although it's basically impossible to properly photograph because of its size. The public spaces are attractive, clean, and interesting. It's very clear that a lot of thought and planning went into everything.
Embarkation: Unfortunately, this cruise was the first time in Symphony's history that the computers were down at embarkation, leaving hundreds of people stuck outside. So for us, it went very poorly, but that's not normal. Once we were in, the processing was pretty efficient.
My cabin was a bit larger than I normally get for an inside--say, with NCL. It was in great shape, and the attendant did a lovely job with it. The shower head was awkward as heck, though, and there was no "normal" washing line--just little weird hooks. That may be normal for RCCL.