Just as a datapoint, the camera is now -much- easier to manually focus. I use either f4.0 or f2.8 lenses and the view thorugh the finder is plenty bright. If I stop down to f20 or so and use the DOF preview, the view (even in bright light) becomes too dim to see, but it pretty much did that with the stock screen anyway.
With the stock screen I literally could not tell if the subject was in correct focus.
I give this product a two thumbs up.
Installation took about two minutes including reading the instructions.
(Low post count disclaimer: not affiliated with Canon or any photo retailer. I shoot as a hobby)