If your neighbour did this as a "freebie" to help you out with your situation (yes, I read your history), you can't complain. But if you paid market value for this alteration, then I wouldn't be happy. It's a poor job. He tried. Not a bad plan, but his cuts and joints should be much better.

As for waterproofing, I don't think there's any way it can be "warranted". the weak point will be where the replaced tile starts and the very corners of the roll-in ramp.

You say you didn't ask for "mosaic", but mosaic tile is the only way you can accommodate four sloping planes with a center drain. Unless you went with a large format and cut them into 4 diagonal cuts. But that's extra work, extra time and extra money.

It will look better once it's grouted and siliconed, but it's not a professional job by any means. I would barely give it "DIY" quality.