Bought this for my trip to Brazil. Best idea ever! Those stupid travelers belts that go around your waist are super uncomfortable, especially in 105 degree heat. The bra wallet is much more comfortable, and while you can't fit your passport in it, you really don't need to have your passports with you all the time. Plus it's a bit more subtle to quickly flip it out of your boobs than to have to lift up your whole shirt with a belt. Another advantage of the bra wallet over the waist belt is that you can wear under everything! (some low cut tops are problematic) But dresses are no problem. I imagine turtlenecks might pose a problem... but who wears turtlenecks anyways?

Downsides include, occasionally people can see it, especially if you're wearing something tight or low cut, or bend over. And when you have to get your money out, it can be awkward, or when you have to strap it back in. The plus of this, is that even if people can tell where your money is, they probably won't be able to steal it.
Also, if you have too much stuff in it, (cards/change/ect) the bulge can be quite noticeable.
Additionally, if you have small breasts, this might not be the product for you. I don't know, if you only kept cash in it, it would probably be fine. It's pretty thin just by itself.

Overall, I recommend! Well priced, and very very handy.