I fell in love with the teak decks on my Nauticat, which are a character defining element of these boats. I must admit though, they also build character in the owners - after a few years of maintaining them. (g)
I agree with the others regarding the potential for leaks in older, worn decks which have not been properly maintained by renewing worn caulking seams and keeping all the teak bungs tightly glued in their screw holes.
However, some boats, including Nauticats, have a solid fiberglass substrate under the teak overlay. There is less chance of water intrusion and no possibility of rotted core with this technique, since there isn't any coring to rot.
If you love the look and don't mind maintaining teak decks properly, then go for it.
True Blue . . .
sold the Nauticat