You at least get to see how the locks work although sailing all the way through the canal is interesting if you have the time. We were all the way through the canal 2 times & did a partial 1 time because it was something different than cruising the Caribbean again & again. It does save on air fare & gives you a view of the canal workings.
Definitely no cons - I've done it 3 times on the Island and will be doing it for the 4th time this November on the Coral. Have also done a trans canal.
If you book the Ferry shore excursion, you'll be taken all the way over to the Pacific Ocean through the other 2 locks so it's just as good as a trans canal ... better cuz you don't have to do a long plane ride. Plus you get an entirely different perspective of the locks from the ferry. I'm not big on shore excursions but I continue to rave about this one.
I cruise the Emerald Princess, Eastern Caribbean on April 16, 2012
The ferry excursion is FANTASTIC!. We went when we were on a cruise with MSC and will never forget that excursion, but you must do it thru the cruise line since it can take much longer than the stated time. When we went there were 300 from the ship on it and we were 3 hours late getting back to the ship but of course it waited for us.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013