There is no simple answer to this.
First off, let's eliminate the new 35mm rangefinder system (the Zeiss Ikon) by Carl Zeiss AG.
Next, the question you ask is much too broad, because Zeiss Ikon produced cameras in a number of formats from a period starting in 1926 and extending to 1972.
As JPD points out, Zeiss Ikon produced cameras but made no lenses. Lenses were supplied by Carl Zeiss and some third-party makers. Carl Zeiss, conversely, never made cameras -- just lenses ... and still doesn't.
Zeiss Ikon made cameras in these formats: Plate, sheet film, 120, 127, 116, 35mm and 126, as well as movie cameras, and possibly others that I've missed.
They made highly sophisticated cameras such as the Contaflex twin-lens reflex and Contarex 35mm SLRs. They made simple box cameras, folding cameras, Instamatics. They made medium format cameras, cameras for pros and amateurs and studio photographers. Cameras for people will little money (Box Tengor and Nettars), cameras for those with money (Contaflex, Contax, Contarex), microscope cameras. They even made enlargers.
This reply is getting much too long.
With just a few exceptions, nearly all of their cameras were made to a high standard -- choice of materials and workmanship -- than their competitors. It's very common to find a Zeiss Ikon camera that can be restored to excellent working condition.
So, yes, a Zeiss Ikon camera is good. There are only a handful of cameras that I feel didn't quite meet the standards of Zeiss Ikon. Overall, however, they're excellent cameras.