Make sure the tile works with your flooring, and consider repainting if the wall color doesn't work with the tile you like. And I think you will need to repaint if you go with that tile as it doesn't work with the wall color.

If your granite has a lot of movement this may be too much. What is the style of your kitchen? This gives me a 50s bathroom floor vibe. Could be cool in a modern retro space but if that's not what you're going for I'd think about a simpler tile. I don't think it's necessarily too dark but without seeing your counter it's hard to tell. I'd err on the side of lighter generally.

Whoops I just saw you do have a counter sample. Something looks off about the tones of the backsplash vs counter. Backsplash is reading a bit green-grey. To be safe I would probably try to match one of the lighter veins from the granite.

You are investing in a beautiful granite counter that costs $$$, if you install busy deco tiles you take away from the granite. A kitchen has many interesting finishes and interest will come from " what you place on the counters" as well. Go with a White subway tile. Look at white glass subway tile, if the classic style is not what you want.

Trust me, you will thank the professional and expert advice you receive from this site.

I love the color of the granite, but I would chose a lighter color for the granite - something in between the cabinet and the granite so that it doesn't over power.