The pattern is unusual and actually very unique, but the way the strips of veneer were applied are normal.

I like the peaks and have seen them often but I know what you mean about the rest of it. That would drive me crazy too. I don’t think I’d be able to keep it. Whether it’s normal or natural it isn’t for me. Doesn’t sound like you’ll be able to live with it either. I feel for ya

It's normal, but I would think carefully about how and where to use such a strikingly patterned panel, consulting with the customer about whether, how, and where to feature it.

Walnut lightens significantly with exposure to light over time, I think you can expect the contrast to lessen substantially as the cabinets age over the next several years.

Looks like a combination of heart(dark) and sapwood. Sapwood isn't usually used in this way.

This is not the fault of the cabinetmaker. Nothing wrong here.

Sometimes that wood would be steamed to redistribute the pigments so the color is more even. Or one can stain it prior to clear coat. It's quite striking, I can see how some would like it and some would not.

If your conversation with the cabinet company or builder was limited to "we want walnut", you might have been expecting an even dark color.

Bookmatched, normally a premium price. If you expected all heartwood, you probably couldn't afford it, even if you could find it. Black walnut is extremely slow growing and having to get 100% heartwood would probably yield 50% waste for an already expensive domestic wood.

I don't really like those horizontal lines either but they'll be less visible as it fades. I think you can overlook them since the rest is so nice.

Looks groovy!

The horizontal lines are part of the grain pattern close to where a branch would have grown in the tree. As others have said, the veneer is normal. As a woodworker, I like the natural beauty of the wood in the door, but I can see how others could see it as distracting.