With the Wii U just releasing, many people have compared its launch to the the HD consoles' launches. Oftentimes people use this comparison to conclude that the Wii U's launch is pretty good. But people should understand that this conclusion could be flawed depending on how the Wii U lives its life.
The PS3 and 360 did not have good launches. By most measures they were pretty terrible. In fact, years after they released, most people still believed they would ultimately be low-selling consoles, probably selling under 40m units. These weren't bad estimates at the time either; the consoles were just selling so poorly. Fortunately, the HD consoles compensated for their weak start by having strong later years. Sales picked up so much that they didn't peak until their 5th & 6th years.
The Wii's life by contrast was very frontloaded and seemed much more like a sprint. It had a great launch and peaked in it's 2nd year. After which, sales dropped fairly hard but it's overall sales were still great. However, what if the Wii had a poor launch? Would it have compensated later on? I don't think so. Unlike the HD consoles, the Wii's life seemed more focused on a powerful start. I don't think it would have had the endurance like the PS360 to compensate for a weak launch.
If I had to guess I would say the Wii U is a sprinter like its predecessar. In which case, its start is much more important than the PS3 and 360's start. That's why the PS360 vs Wii U comparisons aren't necessarily accurate indications for the future of the Wii U. The Wii U may not have the endurace of the PS360 to compensate for a weak launch. I'm personally not sure how the Wii U will live its life, I just thought this was an important point that most people seemed to miss.