This game looks pretty good. I will get it when it comes out and when I know it comes out :P
As for why are WiiWare games looking better than third party retail games. I will explain what's happening.
Small time developers can't afford to make retail Disc games. It's an expensive endouver where they are expected to fill around at least 2gb of the Disc. Where as WiiWare games are topped at 40mb. That's practically 2GB difference. Voice, movies high res textures..... it all adds up. The only companies who can really afford to make retail games are developers who have big name publishers to back them.
Ok so where does that leave us. Big name publishers don't take the Wii seriously as a gaming machine. Most of the projects they make are for quick cash not labors of love. That's why many Wii versions of multiplat games are not developed by the lead studio who are doing it for the PS360. These secondary developers are not the same passionate team. They are cash contracts. They have little interest in pumping out the most awesome game they can with such a tight budget. There is no reason for them to really invest there creative juices. Notice how MHTri looks fantastic where as Star Ward Force Unleashed looks graphically dull. One is a labor of love and passion the other is contracted out game Krome Studio's was it.
So no we know wtf is up with big publishers and contracted studios. So why the hell are WiiWare games looking good? Simple the developers of these games are doing it because they wan't to make that game. They are putting in there passion into the game. It's fun for them to make and play the game. In the end it's the game they want to play. So instead of slapping a few crummy textures the artists, modelers and coders are putting there creative juices to wring out the best graphics they can on such a small amount of space. Since they care they are succeeding where some companies just don't want to.
This games clearly uses tricks and the TEV. The TEV is pretty much ignored by most companies due to the learning curve. The most the TEV ever get's used for is cell shading and even then a lot of companies won't. Heck the you can tell in the new PoP for the Wii and HD consoles. In the HD consoles you can see shaders being used where as the Wii isn't using the TEV.