You will never be satisfied. Better textures, significant upgrades to both lighting and reflection mapping (both are noticeable and require more GPU power to pull off), very good AA, and better framerate. Pretty much every single visual aspect of the game has been upgraded in some way, yet you call it 'small'. If it were just one aspect that was upgraded, you would have a point, but you cannot (I repeat CANNOT) upgrade so many different aspect of the game without more GPU power. The fact is, we're getting to a point of diminishing returns on power. Since games like this already look very good to the naked eye on current consoles, technical upgrades are not as pronounced as when we were moving from SD to HD in the previous gen. Even watching the Killzone demo on PS4, though it looked very good, did not make current console games look bad in comparison by any stretch.

Your earlier predictions were that some things might be upgraded, while another aspect (like framerate) would be worse. You were wrong.

EDIT: I watched the video and was wondering if you had even bothered to watch it.

Framerate: WiiU clearly has the edge here in the more demanding scenes. In addition to dropping to an overall lower rate during cutscenes, the 360 version also 'stutters' a lot, which you can see as almost a split second 'pause' in the screen refresh. Playing the game on my friend's 360, we noticed it does this during races as well (especially whend taking a corner), but it does not do this nearly as much on the WiiU. Keep an eye on the spinning tires on the cop cars in the close-up shot.

Textures: WiiU has the edge here, but this is difficult to discrern when driving at 100+ MPH - It's much more noticeable in cutscenes. Also keep an eye on the textured damage mapping on the cars.

Lighting: This is where the WiiU takes the cake in my opinion. Until I saw this video, I had never noticed how big difference in the night-time lighting actually is. Just look at the pickup truck towards the end of the video. In the 360 version, it appears to be lit no matter what, while in the WiiU version you can clearly see lighting from directional sources interacting with the vehicle in a very natural looking way. The directional lighting on all aspects of the environment are significantly better on the WiiU version as well. I noticed a difference playing both versions on my TV, but seeing them side-by-side really shows this one off.

Reflections: Once again a noticeable difference here. The reflection mappings look much more realistic due to the higher draw distance on reflection maps. The quality of the reflection effect also appears to be upgraded.

Having just played this one for myself, I can report that it looks absolutely gorgeous on Wii U. The lighting, textures, and reflections are exquisite, and there's barely a hint of slowdown.

The only other Wii U game so far that even comes close to it visually is Trine 2 Director's Cut. 

Criterion has put devs like Treyarch and Rocksteady to shame with this title. This, ladies and gentlemen, is how you port a game to Wii U.

You do realize the only reason this port is so good, even superior to the others is because of the extra dev time right?
Both the Batman and COD game were rushed ports for launch.

Says you.  The developer says it was because of the extra RAM and alluded to the fact they actually got to work with finalised dev kits.

considering how small the upgrades were i'm sure, the 360/ps3 version could look just as good with extra dev time, the only thing i noticed in the direct feed captures for DF is thr better reflection mapping on the road, and before people get riled up, just look at ninja gaiden RE 3 on 360/ps3 its runs so much smoother and looks better then wiiu version, not to mention it looks and runs better then vanilla ninja gaiden 3, extra dev time always helps a game look better, just look at forza horizone it looks much better then then need for speed most wanted on any console.