I'd call that unacceptable. What is happening on the front part? Looks like tiles going every which way.

What does your contract say regarding acceptability of work and your options if you don't like it?

THIS is what you get for the ridiculously low bid. IF the bid was for all the tile work (floor / shower / tub surround) that should have been a red flag. For work of this scope, I would expect to pay at least $12k in labor...and even more if the tiles were not rectified.

Say goodbye to your tile cost, the money you have already paid, and this installer. No, I wouldn't pay him another cent. Don't rip anything out before finding a new installer who will document all the "wrongs" so you have proof if and when the first guy balks at not being paid. There is a reason that so many people choose an acrylic / cultured marble product $$ over tile $$$$. I'm so sorry you didn't perform your "due diligence" before undertaking this project.

Are we talking Eureka, Roundup, Two Dot, or Miles City? Yep, I'm familiar. Truly, this guy doesn't have a clue as to tiling...and we are all terrified as to the waterproofing attempt behind said tile. Due diligence; Pro tilers love to show off their work (album of before & after shots with closeups), they are happy to provide references to clients who will allow on-site visits, they are the Pros that actual tile shops (they sell only tile - not tools, or grout, they do not have pallets of tile) recommend as installers and the shop will vouch for their work. Here are some sites to read:

https://www.google.com/search?source=hp&ei=UWe2W5KDDNHEswXppoWIDA&q=tile+setting+standards&btnK=Google+Search&oq=tile+setting+standards&gs_l=psy-ab.3..0i22i30.3805.9575..10814...0.0..0.142.1864.21j1......0....1..gws-wiz.......0j0i131j0i8i13i30.KnBcAXi849s

Sadly, if you can't find any better talent out your way, I think I would opt for one of the other choices such as Onyx Collection or US Marble. Most decent carpenters can cut and fit the panels.

You hired the cheap hack. A master bath averages 50K, with at least 20% of that or more going to the tiler.

Hire a real Pro with a clue. He won’t be $1.98.

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

This may be of help, contact your "local" building permit office, in person (bearing cookies would be nice), and throw yourself on the mercy of the clerk. If they have issued a permit for (what will be) a $500,000+ home, you might be able to persuade the General Contractor of said home to tell you who he is using for the tile work. That tile guy might be willing to do your bathroom after he's completed the big house. I miss MT, there's nothing like driving 2 hours, one-way, to eat oranges & onions at the Jersey Lilly before witnessing the Lt. Governor perform the First Flush of the newly installed piped toilet.

https://www.ceramictilefoundation.org/find-certified-tile-installers