Why EPS is still requested
EPS (Encapsulated PostScript) is decades old, but sign makers, embroidery services, promotional-product printers and stock sites still ask for it because their workflows are built around PostScript. It carries vector paths, so the logo scales to a banner without blurring.
What carries over, and what does not
Paths, basic shapes, fills, strokes (width, caps, joins) and transforms convert exactly. EPS has no transparency, so semi-transparent shapes are drawn solid. Gradients are filled with a flat fallback, and text and embedded images are skipped: convert text to outlines in your design tool before exporting.