It looks like the Gecko is a guaranteed Mermaid Scale dropper. (please correct me if I'm wrong, but I'm getting Mermaid Scales every time, and I think it's 3 every time)
+ It's a multidropper, also dropping Water and a chance for Fish and Glimmerdust!
That's pretty awesome with only a 5 hour timer. Especially if you don't have many Mermaid Scale droppers yet.
I got the White Lion today, and the Autumn Treeple a couple of days ago.
I'm still waiting for the Cockatoo and I probably can't resist another Gecko.