Review (4/5): On the fence...
TL;DR: Good product, but no significant space savings.
My wife travels frequently and we were looking for a way for her to not have to take the large suitcase to haul her regular hair dryer and diffuser. Since this is universal, she should just be able to take this to use with the hotel hair dryer.
However, this thing is very large. It is much larger than the diffuser for her regular hair dryer that just snaps on. But it is slightly smaller than the regular hair dryer + diffuser. I wish it was more compact for traveling.
That being said, it works as well as the regular hair dryer and diffuser, so you don't miss out on anything in terms of effectiveness.