I really don't know what the big deal is. They are just a way to allow more balcony cabins to be built into the ship design. This more revenue for the cruise line versus an oceanview. Its just a balcony cabin. Yes the balcony is overhung a bit by the life boats but unless you regularly sunbath on your balcony its probably a benefit because the shade of the lifeboats will make standing out there more enjoyable because it will be cooler. And yes, you are closer to the water but there are still 3 decks (1 passenger and 2 crew) before you get to the waterline so it is father than it looks.
I think you will find it to be enjoyable but if you normally book a balcony you really are not savings that much money with the cove unless you book a aft wrap or other premium deck balcony. Try it and find out.. it would be a shame if you would have to book another cruise because you didn't fully enjoy the cove balcony.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007