Norwegian Sun has the best organized and fast embarkation of all the cruises I've take.
The ship is small, so you feel crowded especially at the buffet area. There were few choices of food and they are not that great. We had cruised before, and so far Norwegian Sun services are not that good as the Princess, but they are cheaper.
We sailed from September 11 to 20, 2011 - this cruise was the last cruise of the Baltic this year, after that they reposition to the Caribbean. During this time of the year, the Baltic states are cold and rainy. It is probably better to take the cruise earlier than September to get a better weather.
I like the ports of call especially the 2 nights in ST. Petersburg. Except for the weather, SPB was the highlight of our trip.