Recently I got my hands on the latest Jelly Bean (JB) released by eybee1970 from xda forum, a guy with quite the reputation with his remarkable Rocket ROM series ever since the Gingerbread release. I am quite satisfied with this Rocket ROM v1 JB even though it's just a leak version of JB but it's quite stable, fast and smooth as well.
The downside of this leaked ROM is that there are some apps crashed when opening it and some of them have unexpected behavior. However, getting to this JB leak is not easy due to several apps are force closing like the default music player when playing a music, Samsung keyboard that stays as upper cased when "auto capitalization" are checked and some other apps. Music player can be fixed by patching the system/app file and fix permissions after patched. In overall, this ROM need an experienced user to fix the problem else the phone will stay in a bootloop resulting in need of flashing the ROM again.