Well while looking for an Intelligence Victory (read governmental/military intelligence) to write about for an entry in an essay contest that would have something to do with my graduate thesis I found this instead. From the looks of it it seems the Chinese have managed, on the surface, to have made one or more copies of F-35 JSF (Joint Strike Fighter). There are some external differences, the biggest one being a twin engine layout vs. the JSF single engine, but this is pretty spot on as a whole. Now as for the internal similarities, only time and intelligence (of all sorts) will say if this is a more than external copy of the JSF.
I would suggest reading the Globalsecurity.org article and follow to the china-defence.com article. From there stick to the reputable sites, be discerning of where your info comes, and watch out for certainties rooted in speculation. However, looking at what is being described, barring this is equivalent to many of the Iranian new weapon system releases (aka: faked for disinformation and/or propaganda) the Chinese have succeed in technological surprise. Only last year did Sec of Defense Gates say that the Chinese would be able to operationally test a gen 5 stealth fighter by 2020 or so. Well that projection has been upset but we will have to wait and see what this actually portends, because this could be just a tech demonstrator or a flying but not fully operational (no weapon systems, advanced radar, or production engines) prototype and not a the first step in China's fielding of such an advanced aircraft. Only time will tell us what this all means.