I started to run with an HR monitor (polar strap) about 2 years ago, and it has been nothing short of amazing the addition of objective data to a workout can add.
As you train, you can see the improvement in the cardiovascular system in weeks and months.
Does a HRM help lose weight? Probably not.
Does HRM help to objectively improve your health? Absolutely.
Now we need devices we can use in the water too...