Rugged and effective.
You can upgrade them with third party lenses.
The Ektagraphic lines of projectors were an upgrade, but that is as much related to the ability to handle commercial use (think travelling salesperson or business presentations) as it is to projection quality.
It is a well built projector. The Carousel projectors out sold all the others because they were better built and depended on gravity to move the slides rather than pushing or pulling.
The lens is typical of a Kodak carrousel. It's OK. Other manufacturers do make lenses for the Kodak projectors. I have lenses for the carousel ranging from 50mm to 300mm.