It's purely cosmetic, unless you get the front clip that includes HID's. I believe (but confirm with someone else) that it consists of new front bumper, headlights, hood, fenders, radiator support and radiator (there might be more). They tend to run between $1500-$2000 before installation.
Is the conversion worth it? That's completely a matter of opinion. Are you a JDM *****? Do you like the way Accords look? Could you not find a way to spend $1500+ that would actually make your car faster? (Is my bias coming out?)
That said, it does look good. Just not what I would spend my money on.
i beg to differ that, some folks prefer to do the outside cosmtics b4 upgrading motor, me however i built the motor, as i was buying the jdm front piece by piece, and i did install my self to save some cash, so its a preferance thing yes, but car is totally different with taht front, it dontlook like an accord, adn honestly if we did some testing u never know the jdm front might be more aerodynamic then the usdm front, i know jdm front is lighter, so that serves some mechanical purpose, the rebar is about 20 pounds lighter in itself, i think its worth it, to get people to turn there head around at ya, now i think the HID headlights are a waste but other then taht the jdm front is a +++++