Keep in mind that if your Amiga is PAL then all the screens will not scroll very well as it performs 50Hz->60Hz scan rate conversion.
Also keep in mind that (like all external scandoublers) it is not 24-bit so you will miss a few colours in AGA games.
Oh, and Ambrey are not the makers of this device... just the shop. This is a
Cypress CM-397. It has been discussed many times over the years on Amiga.org
Shame the price wasn't just a little bit less (~$60) and it would be great.