I'm not an expert, but I would say it could be fine, if it is well laid out. In other words, what is important to the overall appearance is where the breaks are in the tiles that have to be split where a whole tile won't fit. Since it is such a small space, you'd probably be safer going with a smaller scaled tile.

Yikes! I'm surprised you can open the door. I'd Look for a porcelain 2 to three inch mosaic on a sheet 12 x 12 in slate or a deep stony tone. And tone in the grout. I don't understand the other photo with the vinyl?

https://www.build.com/daltile-cs33mscerp/s1319404?uid=3134687

Actually I was thinking on using actual slate. Both landings require a total of 50 sqft of tile, and that taking into account the 10% loss, so it's not a lot. Is there any reason I shouldn't use slate?

I was looking at this tile Tile Shop Slate Tile , but not 100% sure it's not a bit too dark for my entry and which size would be best, they have it in 12x12, 16x16, 16x24. I will remove the carpet from the stairs, and stain the treads and the posts a dark brown and paint the spindles and raisers white.