A couple cruise lines just changed their smoking policy (ecigs included because "it looks like" smoking) , as far as I know there is only one left that will allow smoking on the balcony of staterooms. Most designate an outdoor area and in sections of the casino. That said, Norwegian now specifies that one must be an "active" player to smoke in the casino so there is some variance between cruise lines...
My past experience on Carnival (prior to their new policy) we really had no issues, we just did it away from the masses, we never vaped on the open pool deck as smoking also isn't allowed there, however we went one deck up found a nice spot and vaped to our hearts content, many times we were joined by others, 10-12 at some points during the cruise. At the time our balcony was free game and that was very nice in the mornings with my coffee waitin' on the sunrise. We didn't do the casino much as that area was very overpowering with smoke even for former 30+ year smokers that we are. I can honestly understand how the non smokers must feel in that instance having to deal with it. We also vaped in our room some, it's obviously not allowed but there's really no way anyone will know unless you fog the place up and the room steward happens to go in or knock on the door, even then it's not likely they'll say anything...
Basically just be smart about it
