If you read the
lens reviews you'll recall the fourth reviewer, and I agree. It's not a fine-arts lens. It's a knock-around lens, good for being there, no great loss if it's damaged. It's one of the three lenses that commonly resides on my ZX-M, the others being a Super-Lentar (Tokina) 21/3.8 and the other a Vivitar Series 1 Version 1 70/210/3.5, both of which are rather better. But I can be more careless with the 28-80. Mine has a loose build, or maybe it's just loosened up over the years.
I'm culling out most of my manual zooms. I have my reasons. This, and a Tak-A 70-200/4, and the Vivitar, are the only ones I'm keeping. It's no gem but it's no cull either. If you get it for a reasonable price, fine. If not, it's nothing to weep over.