I have to say my wife and my 7 yr-old are absolutely loving our new Wii U that we got about a week ago, and we barely have any games for it yet, just the two Mario and Luigi titles the bundle came with. They couldn't care less about my PS3 or 360, the Wii U is by far getting the most use in my house. It's just a fun game system for the whole family.
And as mentioned above, it's sitting behind my AV cabinet even after hours of use it's still cool and dead silent, pretty amazing compared to my other two systems which need good ventilation and neither are silent. We're still trying to figure out the Wii U game pad. It's neat in that you can use the Wii U normally without the TV (the screen on it is great) but it'll be interesting when games really take advantage of it as a second screen; hope Watch Dogs does something along those lines.
All in all, we're totally loving the U and the upcoming games (e.g. Mario Kart 8, the new Donkey Kong etc...) have us even more excited. I think it's clear Nintendo isn't competing for the same market the PS and XB are, they're essentially in their own little market. Once the Wii U comes down further in price, maybe get rid of the base model and just have the Deluxe, start bundling the new Wii Sports Club (same way they did the Wii Sports with the original Wii) and you'll see it really take off.