The jury is still out, to be honest. There is nothing wrong with the Wii U's early numbers, especially considering supply constraints, but I think we still need to see how multi-plats that release on all three systems at once fare on the Wii U. People who want multi-plats on Nintendo consoles had better gobble those up at a healthy rate or it could mean trouble. Right now we're dealing with ports, some of which will likely be purchased as Christmas gifts. Forming a conclusion at this point would be a mistake.
The bigger issue, of course, will be next gen multi-plats, though we probably won't have a clue if the Wii U is getting those until E3 at the earliest. I'm going to assume that Nintendo is trying their best to push the Wii U as a viable platform for those projects. If developers are skipping the Wii U from the start with next gen multi-plats, that would be a bad sign. Hopefully they'll at least give it a genuine chance.