Yes they work great! I have them in my son's room from 3 day blinds and I love them. Right now the sun is blaring on my son's room but there is only a touch of light that comes in. So worth it.
Side note. My husband convinced me to not put them in our bedroom since they do make the room darker all the time. Every morning at 5 when the sun wakes me up I either: 1) go sleep in our guest bedroom that has room darkening blinds, 2) put a mask on my eyes 3) curse and swear this is the day I am going to call the company and get room darkening in my room (now my husband thinks it is a good idea, I just can't fathom getting three new blinds and not using the other ones).