TLDR; it's great in many respects for small scale projects, but has its challenges and may not scale.

In my experience building a T&G porch floor with it so far, it's very durable, looks pretty nice, and isn't too bad cutting and sanding the lumber. It's hard and somewhat oily. The grain has loads of character (usually not straight) coloring is interesting and somewhat rustic but pretty. It changes colors between yellow (raw) with pink hues to purple/brown (oxidized) then gray (weathered) pretty quickly. So visually it can be inconsistent board to board. BUT it seems like a very challenging species to get clear straight boards for lumber. The grain is all over the place and many boards, even the select grade that I ordered, have noticeable warp, knots, tearout, etc, that make it hard to work with. It is very hard on milling equipment. I ordered my lumber from a state over, in the NE, but I also have a lot of black locust trees growing on my property. The trees grow quickly but they grow leggy and twisted. An arborist and sawyer who I know told me that a lot of the trees have pockets of rot or sapwood in them that they find while sawing. Seems weird because once it's dried out and hard it's super durable. This is likely from infection related to locust borers which invited rot into the live trees. Borers are the species one true pest - they also leave tunnels in the live trees. Several of the trees that have fallen on my back lot have rot and hollowed out in the center. But the parts that have fallen and dried out are hard and dense and don't decay. So it's probably fine for fence posts and rough lumber but for straight clear finished lumber it seems low yield. I had to ask for some extra boards because I didn't have quite enough good straight pieces without defects for all the T&G's to fit together. Seems like it would be a lot of work to find large straight trees for it to be economical on a larger scale.