My current apartment is set up that way. The toilet/sink are in their own TINY room, and the sink/mirror is outside of it.
At the time I saw the post, I hadn't thought that arrangement would work at all. I understood why people might like it, but I didn't think it would work as well as it all being in one room.
Sadly I was correct.
There are things you need when getting out of the shower, and it would be nice to have your clothing in where it's warm and steamy. Even now, in summer, I dislike having to go out to the cold apartment to get dressed -- it's going to be awful in winter! Just taking your clothing/other stuff into the toilet/shower part doesn't work. It's about the size of a public restroom stall (with the bathtub attached to that), so there's really no room to get dressed. The toilet takes up fully 50% of the free space. There's no room for a little table or anything, because the door moves through what non-toilet space there is.
The other really big issue is my Kindle. If you drop a book into the toilet, that would be bad, but it wouldn't be anything like dropping your Kindle in. Right now, when I'm not taking a shower, I keep it on the edge of the tub. When I take a shower, I move it to the back of the toilet. In a perfect, normal bathroom world, I'd not move it above/across the toilet so often.
I'm going to see if I can find a tiny tiny little table for next to the toilet. Putting a shelf over/above the toilet doesn't work because that's where the towel bar is.
The bathroom is just a minor challenge. All in all, I like this new apartment a lot.