Yeah - it's always the tilers fault!
I don't agree it's a mess - I agree there are issues but not wholly with the tiler!
You haven't explained the first floor tile problem and perhaps your expectations were too high.
65sq mts and 4 photos of joint variation doesn't make a mess -IMHO.
There are many factors to consider, floor preparation, tile quality, 5mm joints for 800x800 tiles - and we are only seeing photos!
The first issue with the original floor was that the tiles weren't polished correctly down one side. About 1cm down one whole side on every tile was effected but it wasn't something you could notice even when looking very closely. Nobody including myself, the tiler or the boss at tile choice who came to see the finished job at the time noticed. It only became apparent a few months later when one side of every tile started to gradually discolour and we couldn't get the stains off.
That was a tile fault - these things happen and this job was supposed to fix the issue. We couldn't get the same tiles again so we had to go with new ones and I picked the tiler that came with the highest recommendation - and he's got paid exactly his going rate for this. It wasn't done cheaply.
He removed the old tiles and prepped the floor to re tile as part of the job so I can't say anything about the floor prep but it should be right if he did it.
The tiles look ok size wise but I will remeasure tomorrow and I will stand them up together to check. If they were all different sizes though shouldn't he have told me he was having issues with them? And if there were issues I believe expert tilers can normally make a good job of it anyway by eye?
The 5mm joints were needed to allow some movement with the ufh as the room is fairly long. 5mm aren't pretty at the best of times so the 6 and 7mm ones look awful.
I agree you've only seen a few pics but I'd say probably 30% of the floor has issues like those in the photos if not more because if one tiles out by 2mm the whole row follows that. So every joint is then staggered and every grout line is on that row is then 20-40% wider than the one next to it. Nothing is uniform.
I'm not saying 100% it's his fault. I'm just wondering if I should be complaining heavily or not and posted the photos to exactly for that reason - to see if my expectations are too high and what is reasonable?
While the tiler was doing our job he was happy to critique our bathroom tiling saying it's poor as a couple or tiles in there sit ever so slightly higher than the rest. When someone talks like that it raises your expectations too.
If this was free then I wouldn't complain but I've paid him thousands.