Documentation is thin, so I would recommend this only to experts.
I bought this to use with a Kingston Elite Pro 8 GB 133x CompactFlash Memory Card CF/8GB-S2 to replace a failed original HD in a 1.2GHz G4 iBook. I tested the CF card alone and then in combination with the Syba adapter (using a bare-bones USB IDE adapter) before installing it in the iBook (a laborious process -- I highly recommend the ifixit website for instructions). The 10.4 install went fine and the iBook works again with the added benefit of being totally silent.
While this card has roughly the outline of a 2.5" disk, the provided mounting holes are completely unrelated to the mounting options for an actual disk. I actually had to install it with double-stick tape. The iBook's IDE cable extends to cover the master/slave jumpers on the drive, so the supplied jumper must be removed entirely. Performance is decent, but that's mostly a property of the CF card and not the adapter.
The one lingering problem with my iBook is that it can no longer resume from sleep. It wakes up fine, but it cannot access its disk (ie this adapter) and shortly freezes. I have since seen other adapters which specifically list "Automatic wake up from power-down on host reset" as a feature, so perhaps that would fix it. Even though it would be cheap to try another adapter, I'm not inclined to disassemble the iBook again!