The big pro and the big con of this device are the same. If you are a believer that bio-electric impedance analysis (BIA) is an accurate and useful way to measure things like body fat percentage, then you may find this device desirable. The big problem is that most scientific evidence does not support the use of BIA as particularly accurate. Really there is yet to be an inexpensive, practical way to measure body fat in individuals.
Pros:
-Gives you a lot of data
Cons:

• The evidence is lacking that this data is either accurate or useful in individuals.
  My conclusion: It is one more way to get inaccurate data to make you either feel good or bad about yourself. It is more likely to be beneficial to eat well, exercise regularly, and not look at so much questionable data.