Its doing okay, nothing more and nothing less. Its performing more or less exactly like I thought it would.
The 5.5 million shipped by the fiscal year will be a toughie though, stuffing the channels with 3 million consoles during the january/february/march plummet will be terribly difficult. One also has to consider excess stock from the holidays, shipments are often very small in january even if the sales can be decent or even very good.
4.5 million shipped and 4 million sold to end user by the fiscal year, is my prediction right now. We could easily see sub-100k numbers for several weeks until then and we know that 70% of hardware sales happen in Q4.
Overall, it should manage to sell about 10-11 million units this calendar year, bar a price cut in the fall/winter (which is highly unlikely). It won't break any records but, honestly, from what I can tell by the mood and sentiments in here in the past months, no one expected it to either.

While I agree that the Wii was a sales phenomenon, how is it unfair to compare the two (the Wii U, that is)? Was it also unfair to compare the PS2 to the PS1 (or vice versa) and is it unfair to compare the PS3 and PS2 as well? DS and 3DS? I don't get it.

Yes it is unfair to compare Wii U to Wii sales.  Just because a system has a similar name doesn't mean it's a similar system.  The two consoles are drastically different.

Yes it is unfair to compare Wii U to Wii sales.  Just because a system has a similar name doesn't mean it's a similar system.  The two consoles are drastically different.

And whose fault is that? So what you're saying is that Nintendo simply built a better console with the Wii and that makes it unfair to compare the sales of the two?

The problem is that the Wii U is trying to be two things at once; a Wii with better hardware and a "hardcore" HD gaming console like the PS360. Its kind of suffering from a split personality. The Gamepad is having much less impact than the Wii-mote but that's still not a valid reason why comparing the two consoles is unfair, if anything it just shows that Nintendo have made some pretty poor decisions lately (which is my point).

By the same logic, isn't it very unfair to compare the Wii to the PS3 and 360? They're drastically different consoles, even more so than Wii U - Wii, we should not compare the sales then. Applying an argument when it fits and then not applying it elsewhere is a silly and illogical tactic, thus it is my opinion that stating that comparisons of the Wii and Wii U are unfair are absurd. Is it only to be compared to the PS3 and 360 (yay, it had a better launch than them and this is significant yet the fact that it had a much worse launch than the Wii is irrelevant)? Only the PS4 and x-box 720? Then, again, why was the Wii ever compared to the PS3 and 360? Aren't the PS3 and 360 competing with the Wii U just like the Wii? Exlcluding a 7th generation console for the purposes of comparisons like this seems backwards, especially on such thin grounds.

You're going to have to come up with a more compelling argument than "they're different and should not be compared". The 3DS and PSVita/PSP are also very different consoles, should we not compare them either? Besides, the Wii and Wii U aren't really that different when it comes down to it, they're essentially trying to do the same thing by the same means (unique controller and low entry price to entice casuals). The Wii U is a product of its time and has a lot more functionality but in essence its trying to go down the same path the Wii trod before it.