We originally did, but backed out, but that was us.
One of the reasons we opted for it was because if you used their air package and hotel, you could stay more than the normal two-day deviation, and we wanted to stay an extra day in Rome.
We also looked at the flight combos on ITA Matrix for similar flights (RIC-ATH, FCO-RIC) and realized that most of the flights either had super-short connecting times (under 2 hours) or very long ones (6 hours or more). We did find a few in the three to four hour wait range which we deeded to be ideal -- and figured those weren't going to be the ones selected.
Once we did some math (figuring the upgrade for booking our seats, and the lesser price of a hotel in a better location vs what NCL was charging), we figured the difference was minimal, so we sat on it until air tix became available, bought our air and canceled the NCL air package.
But, as they say, YMMV.