The Credits theme to Invisible War has got a similar vibe to the Credits theme in the original Deus Ex: it's got a cyberpunk, synth rock vibe to it. It feels a bit darker than the original Deus Ex credits theme but then again the sequel itself feels a lot darker and grittier.
Like the original Deus Ex, Invisible War offered multiple endings. There are four you can pursue although I'm not sure if any of them are exactly ideal: you can either let the Illuminati control the world from the shadows again, let the world be governed by a benevolent AI which is linked to all of Humanity, release a nanite swarm that purges all modified humans of biomodifications or allow the Earth to become a post-apocalyptic wasteland where only the Omar survive (a cult of cyborgs that belive in posthumanism).
You can get the Deus Ex: Invisible War soundtrack for free here on Choicest Games by visiting the Free VGM Repository