I have always thought that Odaiba is underrated. It is a great little island to visit for the day to take in some shopping at venus fort or the other shopping galleries. There are many restaurants that offer an incredible view of the Rainbow Bridge at night. As for the Park, I wouldn't even compare it to an American park just like I wouldn't compare and American Park to Odaiba's. It is a nice place to relax and unwind and watch the boats go by with a backdrop setting of the Rainbow Bridge. If anything, it is more exciting than most parks because you are able to watch something other than the wind blowing in the trees.
An amazing shopping mall....as Gabriella mentioned, it is like you have been transported to Cesar's Palace in Vegas. Tons of shops and restaurants. Convenient lockers for you to store your jackets and bags. A lot of open space which is a novelty living in Tokyo.