Shiloh Shepherd supposedly came about because a GSD breeder started to ignore the breed standard and just breed for good bone structure, hips, health...and supposedly bred for the 'olden days temperament' of being family friendly, calm, strong nerves vs the neurotic mentality of a lot of the show lines or high energy land sharks like a lot of the 'sport' GSDs.
The end result was a dog that was more square in structure than a GSD, significantly larger, and had a longer coat.
Sounds good in theory.
However, there are some real world problems. Many people especially mainstream GSD folks challenge how much of a problem health and temperament was as well as how much it was 'improved' (often sighting that bigger dogs are more likely to develop hip displasia, so even if penn hip scores are slightly better, net wash due to size increase. I personally think for the most part the GSD community was being overly defensive as they saw the existence of the shiloh as a criticism of the GSD breed as a whole.
The other problem was there was a big personality clash amongst the create of the shiloh breed and a lot of early adopters, which caused a split in this formative breed. This lead to all sorts of confusion, and also lead to anyone who had unregistered, oversized GSDs to be able to claim they were Shilohs. So a lot of the unhealthy unstable dogs you see being passed of as shilohs are shiloh frauds.