Like any descriptor of someone being attractive or good looking, there's a time and a place where it's appropriate or creepy regardless of the actual words and phrases used.
I dont like it, its opposite would be "eyesore" which is tremendously insulting in particular as both terms refer to marks of ones appearance one has little to no control over. And if there are people who are "easy on the eyes" then there are people who are "eyesores".
Also I have never seen it used in a nonsexualizing manner.
"A sight for sore eyes" however is a goat compliment.
To me it evokes a mentality where other people's appearances are only considered through the lens of how they serve the person speaking. I'm not a fan. Even where complimenting someone's appearance is appropriate, I think it frames the compliment as "you're not like those uggos I hate seeing"