Great city and we really enjoyed the boat tour. There are multiple tour boats and some of them really overcharge tourists. Do your homework ahead of time. Also there is a big sticker shock at any restaurant. We got a decent meal that would cost $100 in the US but it was almost $200 in Copenhagen.
In Gdansk we had a woman in her mid-fifties who really knew the town well but English was her fourth language after Polish, German and Russian. Also she was not capable of controlling some of the people on the tour even though we were only ten. The benefit of the small group was that we could see alter the tour to specific spots. The Old Town was totally rebuilt since nothing was left standing after WW2.