not that impressed..
First off i have no personal experience.
But they ran a test with different brand adapters in a consumer format on TV here very recently (a few weeks ago). They tried to stream DVD content over it in different houses and to different location within one house. Of course the whole thing was not very detailed, but the test setup was probably not too broken.
Their conclusions were mostly that
a) different adapters had vastly different performance.
b) house installations also made quite difference - for one quality of lines, then whether the sender and receiver were on the same fuse or not and finally also devices interfering as mentioned in other comments.
Since they only tried DVD they did not test peak rates, everything that was constantly over ~10mbit/s was equally rated as "ok".
However some adapters already started out with maybe 5mbit/s floor under the best conditions they tested, others were capable of staing above 10mbit/s floor for most installations and distances and only fell clearly below it under "extreme" circumstances (this were perfectly normal houses tho, not in an industrial environment or such).
Either way, depending on what you want to do with it it may work out for you.
But personally i get annoyed by my current 100mbit/s ethernet (maybe 20-30mbit/s effective).
If it's a *new* *wired* application it should at the very base compare itself with 1GB ethernet and not 10mbit/s ethernet that was available "decades" ago. Just IMO though.