I don't think Halo 3 was a complete failure in terms of visuals. There were some nice areas, and if Halo ODST looks at least that good, then I'm fine with it. It would be nice if they improved character and weapon models, but whatever. I don't know much about the gameplay, but as far as I understand, it's basically Halo without Master Chief, and with all the reasonable changes that comes with removing the super-marine from the equation. And with less garbage story about confused intergalactic extremists and various adaptive diseases, it's definitely promising.