It's fairly good itself. With the Fit Meter, it's very effective. When you choose a target (say, lose 3 kg in 3 months), the game tries to estimate the required number of kilocalories to burn, and gives you a goal per day. You clock up the kilocalories through walking/moving (Fit Meter) and through using Wii Fit U. It keeps track of your current number of days in a row that you've reached the goal. I'm up to 40 days in a row, I think. And the goal isn't trivial, either. To give you a sense of it - if I spend the day at home, I tend to get to about 300 kcal or so. My current goal is 990 kcal.
To get the rest, on days that I'm at home and not otherwise doing much, I go out on a night and walk around the neighbourhood, which has enough hills to help me clock up the calories more quickly (the Fit Meter tracks elevation, and adjusts calories burned accordingly - you burn more when walking uphill). Today I went for a walk for 80 minutes, am currently at 834 kcal, so I'll have to use Wii Fit U to get the rest of the way - it'll probably take about 40 minutes or so.
I used "fairly good" to describe Wii Fit U itself. My only disappointment is that there isn't a large number of new games within it, and a few from the previous versions have been dropped (like the one with the candle, where you need to be as still as possible).
One specific one to mention, because I was really surprised by one of the new modes - "Orienteering". Uses only the Gamepad, no balance board, and you're given Miis to find around Wuhu Island. You move by walking/jogging on the spot... the game detects the movement via the gamepad alone, and works remarkably well.
I'd definitely recommend it if you want something that will help to motivate you to lose weight. Since the Fit Meter does the job of pedometers much more expensive than it, and you get the game for free (right now) using it, it's worth the purchase.
Thanks for that, very useful. I think I might go for it.