Yikes, that's ugly work. Even though white grout hides alot of sins, you should not be happy with the slivers in the corner and all the chipped cuts. They are either using an old saw blade or don't know how to get a clean cut. What is their plan for the exposed tile edges in the niche?

this looks awful, not acceptable - I have done tile cutting and laying myself that is much higher standard than this

You paid the tuition on hiring cheap hacks. Now, get ready to rip it all out and start it all over. Hire better this next time.

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

Is that a wood window in your shower?

No one said it yet ... what type of waterproofing did they do?

Between the varying grout widths, the chipped tiles, and the slivers in the corners, this job would not pass my diy standards. Uneven corners seem like the least of your problems, but the correct way to fix those is before the tile are laid. Fix the problem in the substrate by building out the corner.

I think the greatest part about that is it appeaars he used a lippage system. But other than that it looks like he gnawned off the edges, but how or why? Did he make his own tile?

That looks like a VERY UNPROFESSIONAL job. I'd cut your losses if I were you and have it done right by someone else. Those are unfinished tile edges. That is an absolute no no. Water will get in there and cause all sorts of damage. Any licensed tile installer would know better. you need something called a bullnose tile for the edges.

Hell no is that acceptable.

Oh wow that’s bad. Get them off the job. They simply don’t know what they are doing. Let alone have the right equipment. Very harsh lesson for you. Hope you haven’t paid. They may to try to fix it to make you happy”short for get paid”. Don’t let them.

What were they charging you for the job?

I have a visceral reaction to what is happening to you because I have just lived it, and now I am on the other side, with a beautiful, properly constructed bathroom.

Last year, the bad contractor said I was too hard to please because I questioned why they didn't do a pre-slope for my shower floor. Then I was too hard to please because I asked why they built me a moisture sandwich for my shower walls. Then I was too hard to please because I asked them why they weren't using good cutting tools, spacers or levelers and my tiles were all wonky, jagged and spaced out weird and crooked. They walked off the job in the middle of a bad bad tiling job because they were sick of my questions.

Nine months later, the judge didn't think we were too hard to please, and awarded us the total cost of the re do with an excellent contractor (found thanks to this forum).

Make lots of contemporaneous notes, take lots of pictures, get the TCNA manual and read it. You can pay for a download; I think it's about $40. Get an inspector (pay them) to come and do an inspection and write you a report of all the stuff done wrong and not in keeping with the TCNA manual. If you can't find someone to do that, read the manual and create your own report. We filed in county court, not small claims, represented ourselves, and it worked out to our favor. This was almost a year after the new excellent shower and beautiful bathroom was completed. You will want your bathroom back, so will probably need to re do your project before knowing if you will get any money back or not.

Get educated, get the job done correctly and then deal with the money side of things. The judge was pretty cool with us, the clerks will help you figure out what paperwork to file, and you can learn a ton of stuff online for your local jurisdiction. If you're lucky enough to have a lawyer friend or relative you can ask them some questions or ask them to look at a document before you send it. That's what we did, but the lawyer relative never came to court or wrote anything for us, just kindly talked things over with us as we went along. The crooked contractor came with a lawyer in a cheap suit, and couldn't explain why they did such a crappy job. Oh, we had it written in the contract that they would construct the shower in accordance with the TCNA guidelines. That helped because the contractor couldn't tell the judge what those initials stood for. But even if you didn't do that, having lots of pictures, notes, and a real tile expert's report will help. It also helped that we had proof that we gave the contractor multiple chances to remedy the situation. You have to do that. If you just out and fire them at the first sign of trouble, then you are the bad guy. You need to make contemporaneous notes of all this and make sure that you have written proof (such as emails) that show you gave them a few chances to fix things. That was important to us; the judge specifically asked about that and we showed her the emails.

In the meanwhile, you want to get your bathroom redone. Maybe someone on this forum can recommend a real pro in your area if you give your city or zip code. I can't remember the names of the 2 or 3 organizations that have a referral service for tile pros, but maybe someone on this forum can provide that info. For me, unfortunately, there was nobody in my area on those particular lists. A direct referral from a GWer is what helped me when I was at my wit's end and asked for a referral near my city. After that I had complete success and a beautiful bathroom. The pro I hired is so wonderful, professional and careful, I'll never hire anyone else. I'm trying to get all my projects done before he retires or moves.

A note regarding some comments on this forum. I have received tremendous help from the kind and generous people on this forum. I don't think I could have completed my kitchen or bathroom without the help here. But every once in a while there will be a rude and presumptive remark that implies or straight-out states that you hired cheap and so the disaster is your fault. The bad bad contractor I hired was not cheap. Actually, almost exactly the same price as the re-doing excellent contractor. Sometimes you think you are hiring someone great, you reject the ridiculously low bids, you ask lots of questions, but you end up with a crook anyway. I think it's rude for anyone to accuse the homeowner of trying to do something on the cheap just because they ended up with a horrible contractor. We certainly didn't go cheap, ended up with a hack, and I got comments like the one you got above. So don't feel bad or ashamed. You are not the crook, they are.

Good luck.

"i reckon its best to cut my losses and try and get in an expert to salvage this bad tile job."

Yor best bet is to cut your losses like this guy then hire a real pro to COMPLETELY rip out that hot mess and redo. Hopefully you have not paid the "tile setter" in full.

I mean I honestly have no idea what the hell he did, that does not even look like tile?

The edges are the way they are due to cheap or dull tile blades. That type of porcelain is commercial strength. The installer should be using a diamond blade to cut the tiles. If it were my job, the installers would be ripping it all out and replacing on their dime.
They should have used bullnose around the casing.