Halo has and will always have a special place in my heart; which is why i hope 343 Industries doesn’t screw it up in Halo 4. Halo Wars was pretty but I don’t feel it advanced the story in a particularly significant way. That said this trailer suggests that some of the old magic so carefully crafted by Bungie won’t be lost.
Halo (whilst fairly linear in story) has always been about presenting enormous environments. While you may not be able to get to most places visible in the distance, the worlds still felt huge. But it’s a teaser so who knows. Q4 2012 can’t come soon enough.