It looks like you will have to do a fair amount of filling staple or nail holes -time consuming but if done right can look fine. . Do you know what kind of wood they are? were they originally finished under the carpet? Is the finished wood on the outer edge the same wood? Blotchiness happens with improper prep and/or certain varieties of wood - maple, for example, doesn't take stain really well (so I have been told). But oak would likely turn out well.

Which look do you prefer?

Your treads look like it has lead paint on it. Test first before you sand.

"Are these stair treads worth refinishing?"

Yes. They will look great if you do the work.

Thanks all! I believe they are mostly oak, they originally had carpet over. I think they stained the edges of the wood thats not covered in carpet

You can give your staircase a fresh look by painting the risers and staining the threads.

You can also use a wood conditioner before staining, if you are worried about blotchy.