This was a great deal on sale. It truly works to totally black out light like hotel curtains do. Easy to use with  decorative tab curtains. Don't know if it will make a difference keeping room cool or hot and energy efficiency but that will be an added bonus if so. Photo shows the room darkening curtain on the left with the liner and the curtain on the right without the liner.

Pros: Great at blacking out light totally
Cons: None