As a rule of thumb, those screw-on in front of the lens attachments are not the greatest. You can expect softness and distortion. But sometimes, it's acceptable.
When you choose an adapter, just make sure it actually fits! And I'm not talking about the filter ring, but the lens itself. I have some by Yashica that come so close to the front element that simply using a filter prevents the lens from fitting.
Also, most of the time you can use them with a step-up ring, so don't worry about the filter size too much.