I'm sure there will be an improvement over the lifetime of the console, but it's worth keeping in mind that the paradigm shift from PS2/GC/XBox to PS360 was much greater for developers than the one from PS360 to Wii U. That said, there are certainly aspects of the Wii U architecture that will lake a bit of getting used to, like the big ol' chunk of eDRAM, GPGPU functionality and whatever other crazy stuff Nintendo's got going on in there. Perhaps more importantly, the only people at all likely to push the hardware are Nintendo themselves, and none of the games they've shown us are the kind they're likely to push the hardware with.
There's about nine months between the E3 build and the final game, so I'd say it should look a fair bit better. It really just looked like it needed a bit of polish, given the disparity between the very nice looking parts and the not so nice looking parts.