Battery operated heated clothing is something I've tried before with socks and mittens, but not a vest. I checked out the web site and here are my impressions:
Pros:

• Looks like it will heat you up and keep your torso warm.
• Multiple sizes and both men's and women's styles
• Lithium battery should be lightweight.
  Cons:
• Web site difficult to navigate, I still cannot really figure out the cost.
• European shipping quotes only, for U.S. or other areas may not be realistic.