This set has it all! It completely caught my eye because it was so bright, which is atypical for a Batman set. If you've seen the Lego Movie, you know Batman only works in "black or very dark gray" ;)
First let's look at the "rubber duck". Don't let its overt cuteness fool you. It's straight from Tim Burton's Batman Returns (you know, the one with Michael Keaton, Danny DeVito as the Penguin and Michelle Pfeiffer as Cat Woman) and was also featured in the first Lego Batman video game (not sure if it's in the second game though). If you take away the Penguin, it's a really cute looking thing, which I suppose is the point. In the movie the Penguin was an unassuming orphan looking for his parents, surrounded by cute emperor penguins, at least that was his public face. He used the rubber duck as a cover to trick people into a false sense of trust in him. Don't worry though the Penguin mini figure doesn't look like Tim Burton's disfigured character. Instead he resembles the 1950's TV show character: a short, rich gentleman in a suit with tails, a monocle and top hat. He comes equipped with his signature umbrella and a radio transmitter for blowing up his two mechanical, armed-to-the-teeth, explosive penguin-bots which each have a radio receiver on their heads. If you take the radio wire off their heads and the dynamite out of their clutches the mini-penguins look kind of cute too.
Batman is a different story. He doesn't hide behind any cuteness... as usual, he's all business! Batman's submersible is something that the Navy Seals or US Special Forces would use for clandestine underwater ops... it's totally awesome! Batman comes equipped with scuba gear, flippers and a harpoon gun that I assume he uses to attach himself to Penguin's duck-tank and pull himself in for a confrontation. In this set, Batman isn't using any over-the-top modified equipment (Iike the Bat mobile or Bat-plane). Instead he is using a simple, sleek, state-of-the-art stealthy underwater submersible and scuba gear. The contrast between his simplicity and the Penguin's disguised cuteness is what makes this set special!
Building: this set is very easy to put together and doesn't take much time at all. There aren't a lot of pieces and the directions are very straight forward and simple to understand. There are more things to build than you might at first expect: both mini figures with all of their gear, Batman's submersible, Penguin's duck-tank, two mechanical mini-penguins and an icy perch, which holds a diamond. This breaks up the instructions and makes it seem like you are building the set very quickly, which I liked.
Bottom line: this set completely captures Tim Burton's imaginative and creative take on the Penguin and contrasts it with Batman's seriousness and his stealthy, ninja like ability to sneak up on his enemies. I'm glad I added it to my collection and I highly recommend it!