This was marketed as an update to the EOS 620: a middle-tier camera for what used to be called advanced-amateurs.
As an update it's kind of a mixed bag. The upgrades include faster focusing and a lot of additional exposure programs and gimmicks. But they dropped the top shutter speed from 1/4000th to 1/2000th, and the x-sync went from 1/250th to 1/125th. A lot of people held onto this camera for the flash sync alone, because the only other one Canon offered at 1/250th was the EOS-1 models.
Cosmetically they're nearly identical. I photographed them side-by-side and if I put a mask over the model number, I wouldn't be able to tell the difference. Same goes for every other angle of the camera. I suppose that's a way to keep costs down.
For more information: Canon Camera Museum
Modern Photography "SLR Notebook" magazine preview: June 1989