The Contarex Bullseye is a larger camera -- larger than a Nikon F, just to give you an idea of its size.
Like all nearly Zeiss Ikon cameras, it's massively built. Attention to detail is impeccable, as the Contarex was sold as a top of the line camera. It's mechanically more complex than most of Zeiss Ikon's other cameras.
The Carl Zeiss lenses by and large are excellent. I've read that the f/1.4 50mm Planar wasn't as good as the f/2.0 version, but I don't have the f/1.4 lens to further comment on this.
I use mine several times a year, generally taking the Planar, the 35mm Distagon and the 135mm Sonnar for an outing. The lenses have two lobes on the focusing ring, which help to focus the lens. Note that the current crop of Carl Zeiss lenses for its Zeiss Ikon rangefinder have a single lobe -- a nice design throwback.
The Contarex controls are straightforward: Film advance, shutter speed dial, shutter release. The only oddball thing is the aperture dial.
Like most German cameras from that era, you removed the back to change the film. The locking keys work identically to those on the Contax.
This was a system camera, so there were scores of accessories available. It had either a standard back or you could use interchangeable backs, which allows the photographer to preload several backs and then switch quickly as needed. It also allows the photographer to switch film types mid-roll.
The Contarex viewfinder is a fresnel screen with a split-image in the middle surrounded by a ground-glass collar. Use either the ground-glass collar or split image to focus and the fresnel screen for composing. The screens are interchangeable.
Aside from the mirror cushion, the camera doesn't use any foam elsewhere (nor did most German cameras), as backs were properly designed to block light.
The sound of the cloth Contarex shutter is unlike any shutter before or since.
In general, Zeiss Ikon camera ergonomics were very good. For the most part, form followed function. Controls are where you expect them, except for the aperture wheel, which falls under the index or middle finger. It's in the same location as the Contax focusing dial, so it's an easy transition for Contax users.
The camera, despite its large size, is very easy to use. The weight helps to provide a stable shooting platform. The Planar lens focuses down to less than 0.3 meters (11 inches). The lenses have good but not overpowering contrast. That's important when you want to take a photo with good shadow detail. Many lenses today are too high in contrast, which is only exacerbated by the limited dynamic range of digital technology.
There were very few third-party lenses for the Contarex. One of the reasons was the aperture control. Possibly, another reason was the intended buyer.
If you could afford a Contarex, there should have been no reason to settle for a lesser third-party lens. Carl Zeiss was (and continues to be) a maker of premium lenses.
It's a bit like buying a Porsche Boxter and then fitting it with retreads.
Today, the Contarex is a niche product, sought mostly by collectors, some die-hard Zeiss Ikon users and others. Prices remain high for the bodies, certain lenses, the film backs and some accessories.