Joseph Ottinger wrote up a review of OpenROV on opensource.com yesterday. I have to say, the summary of the project and potential is dead on (the site admittedly needs to be reorganized, and will be soon). I encourage you to read the whole article.
The project is still fairly disorganized, with files hosted in various places and many manufacturing possibilities. However, the strength of the project is that the base ROV is very easy to build, and the wide-open nature of the project means that any designer can provide enhancements in any way they like (within the limits of the technology and general physics, of course).
An aspiring ROVer could easily build an OpenROV platform that extends the current set of features. Remote controlled vehicles are not at all new—nor is the process of building them from scratch—but the open source approach provides a new set of tools and options for RC enthusiasts who want to take a DIY approach.