You could always get a used copy and see for yourself by trying it on a 3DS since the 3DS plays DS games, but it'll look rather crappy though. Really, the game was tailored to the DS, with the action occurring on the touch screen, the top was very rarely used (outside constellations the slingshot is really the only thing, and then it's either shooting balloons or Pete/Gulliver flying by). Keep in mind too, graphically it's a step down from the GameCube- it's above Animal Island though, but the Wii U doesn't change that, it's still pretty pixelated.
Also, a feature that many seem to overlook is that WW still has is local play to play with others in your town (it's exactly the same as New Leaf where you can play with another person in the vicinity), that of course doesn't work on the Wii U. Since the Wi-Fi is gone, so you can't play with anyone over the internet in either version anyway. The positive is what you said, that they removed the requirement of having to have someone shop at your store to get Nookington's.
In short, with this game being optimized to work on the DS, the Wii U just isn't going to give it the same justice a DS would. However, you will get to experience all the WW-only holidays, and fantastic dialog that so many rave over (myself included). So if that's all you want to experience since the series is likely never to have the Flower Festival returning (that was so fun and easy to win, it's coming up soon too!), then I say go for it.
