Well, as a launch in general they have done poorly. Dating back to e3 2011 they have done a poor job of hyping and communicating what the Wii U is. At launch they didn't have a must-have game, and the Basic Wii U was probably a waste. The OS was not up to par and they had a major software drought. The marketing was awful. The end result is that they have done about as well as MS did with the 360.
So I guess you could say they did OK with the head start. Like the 360 - which had an awful launch with defective systems, no must-have games, etc - the year head start has given Nintendo time to work out the bugs. They've fixed the OS and found what works and what doesn't for their system. They know that their current marketing is awful. They know that NintendoLand is not Wii Sports. They have their manufacturing in full swing which could allow for price cuts.
I liken the current Wii U situation to that of the Sega Genesis. Like the Sega, Wii U has struggled against previous-gen competition. But like Sega, Nintendo has time to react. Sega was able to launch Sonic and a great ad campaign as SNES was trying to find its legs. Nintendo needs to revamp its marketing and develop a killer app to sell the system. Nintendo needs to have this in place by 2014 or be forgotten by time.
Nintendo dropped the ball, because - coming after Wii - they had a shot at being a PS2-like market leader if they brought a product and excitement that could capture the whole industry. They failed at this miserably. But their head start - like any videogame industry head start - is still somewhat of a success because it has given them a 5 million or so install base above the competition and time to work out their mistakes.
