I'm very picky when it comes to tile install and this looks great!

What exactly are you asking us to see? They look well laid out, no noticeable seams between squares. We can't tell if they caulked between the wall and floor, or the slope, and I don't see lippage but not sure I could in that photo. Are you concerned about something specific?

What is really important is not visible. You need to know what waterproofing method is being used under the tile. Marble is just hard sponges held against porous cement board, installed against wood framing. Water can go right through it all.

https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

Nothing specific... sometimes I’ll look at someone’s posted picture and not notice a bunch of stuff all you notice so I’m just putting it out there. I’m not looking at it from the prep work perspective (I know what’s happened in that area in my house) but checking for good finish work. These were quick pictures I took when I visited a job that was completed 5 months ago. Thanks!

First photo, one thing to emphasize with small hex is that the sheets are properly spaced from one another. Some installers get lazy, or get thrown off by the compound slopes on a shower floor, and the between-sheet spacing is so different from the between-tile spacing that your eye can easily pick out the individual sheets set on the floor.

Contrasting grout color emphasizes uneven spacing. Grout color that is similar to tile color can blend and disguise some installation issues.

The niches, I slope niche shelves so water is less likely to pool on them. Niche location? It should certainly be practical. But if it can, it should be somewhat removed from direct water spray. Some people are anal about visual clutter and don't want the niche to be visible to someone standing outside the shower. They want to avoid sight lines of exposed bottles of lotions and potions, for example.

Second photo, consider how the tile is abutted at the outside corners; the wall corner, the door entry, the curb, etc. Sometimes the corners are mitered and the outside edge eased. Sometimes the corners are a simple butt overlap. Sometimes a bullnose overlap. Some overlaps are woven, some are consistent for the full height of the corner.

The curb. The curb should be sloped into the shower for drainage.

Consider that sloped curb with door swing. The shower door needs to swing out so an incapacitated bather does not obstruct door swing. Any type of bottom door sweep needs to be installed with the curb slope in mind. Saloon-type hinges that swing in and out can be better. In the photo above, if one of the cabinet drawers was left open, it could prevent the door from swinging out.

Post-shower, an in-swinging door left open will shed water on the shower floor instead of on the bathroom floor.

Shower controls versus door swing...it's nice to open the door and reach in the shower to turn the water on without having to step all the way into the shower and get doused with the initial blast of cold water spray.

Wall returns...in the second photo, in the top left corner of the photo...see the thickness of the tiled shower wall just outside the shower door, and how it returns onto the bathroom drywall? It's covered by a return of tile into the drywall. That's a nicely finished detail. Sometimes you end up looking at an unfinished return and all you notice is a too-wide thickness of thinset/grout/mortar between the tile and the drywall.

So...points to ponder.