Expensive, so 3*. And I paid £61 from Amazon - now its over £80, so I'd give it 2* for value.
What I was not expecting is that this battery sticks out the back of your lovelly camera - about 12mm - not disastrous, but not great. And its heavy - double the weight of the BP809 your camera comes with. Maybe that was expected, but you do feel the difference because the HF100 is so light.
At £61, you might still consider it better than the BP809, but at £80 I'd say buy a BP809 in silver (or black) and consider if you need a third one of those. Only when you are going to be all day at a theme park/airshow might you need three batteries worth - but then that's why I bought it.
However expesnice you consider these to be, beware:-
The generics being sold out there for £40 are only 1400mAH, not 1780 mAH. That's only 50% more than the standard, not 100% more. (say 1.5 hours vs 2 hours)
And the ones being sold with a charger - they need that charger because odd things happen if you don't use it and charge on the camera, battery level won't work in any case - have a search on Google.
I have used generics before on Canon compacts and have not come unstuck, but the BP819 generics are not cheap, are not fully compatible and and not full capacity. Your choice, your risk.