When someone asks if you like some piece of art, it's reasonable to answer in a binary fashion: Yes, I like it; No, I don't like it.
There's good reason, however, to avoid this.
Here's two ways I like to answer that question instead of saying that I don't like something.
It's not for me.
This recognizes that while you don't connect with it, you can see that others can (and do) connect with it, and that's great. "It's not for me" admits the pervasive subjectivity of art while staying true to your preferences.
I like what they tried to do.
This communicates that while you don't think the artist(s) achieved their vision, you find their vision laudable, and appreciate that they tried. This might even be paired with a conclusion that you actually like it. I know that there are creations that I love just because of what a creator tried to do with the medium, whether it was a piece of music, a TV show, or a video game.
Making stuff is hard. There's no need to fall into the binary of an up or down vote. Respect the effort of creation by making an effort in your opinion of it. The two above are some ways of doing that, but make it your own.