My hubby purchased the Wii system for us for a family gift for Christmas. As an Early b-day gift, he gave me the Wii Fit Plus. I personally love it! :P
I do not have any 'cons' to list for it. Since Christmas, I have dropped 5.5 lbs and for my personal goal, I only have about 8 lbs more to go. This is for my own personal satisfaction as I know for myself and from others that I am not overweight. I am using it for the Yoga and some of the Strengthening positions. The Fit Plus (balance games) do get the heart rate up, and make it so that as you are trying to attain a better 'score', you are working, burning calories, yet you are having fun at the same time.
You have to remember tho... This is a small part of the process to weight loss if this is your desire. For myself, for the new year, I have also taken my diet into consideration as well. When you are trying to loose weight, one MUST INCREASE water intake and WATCH meal portions, and SLOW DOWN on snacks... you also need to make wiser choices by eating better (nothing processed/ fatty/ salty, etc.).
It is not a matter of doing the routines daily, but if you at least do these routines every other day, you should notice a big improvement overall to your well-being and your body~ as with any fitness program.
EDIT:
Oh~ and another thing I love...
When I am on the balance board, my son will do the same thing I am doing. I feel great when my son does this as he learns the value of fitness vs. just sitting and doing nothing (or playing a hand-held). My son is very active on our treadmill and stationary bike~ he loves to work-out with us~ and he's only five. If he keeps that, he will have a great wellness value with him for life. :)