The two maps shown so far look pretty good IMO but I hope Halo 4 will have more vehicle friendly maps. One thing that bugged me about Reach was the lack of big open maps and the ones it did have were neutered by taking out the Gauss Hog and Scorpion. I would actually like to see some Maps from Halo 3 return such as Sandtrap, Standoff, Avalanche and Rats Nest.
Sandtrap and Avalanche are great for big open vehicle combat with Avalanche probably being one of my favorite Halo 3 maps in general. Standoff and Rats Nest are smaller but allow for some good Warthog action. I’m not necessarily saying we should get complete remakes of these maps but I would like Maps which take inspiration from them at least.
Forge World from Reach was a good idea in concept but after a while everyone got tired of playing on pure grey maps. The easiest way to get over that would be to add more stuff to play with. Instead of having nothing but Forerunner style walls and architecture, mix it up with Human and Covenant stuff as well. It would also be interesting to be able to change the time of day. I liked how Sandbox was similar to Sandtrap but at night with large stadium lights.
This is just my opinion. I have faith in 343 I just hope they have plans for more vehicle friendly maps.