I planted the smooth luffa vine this growing season and I have to say it is a bit of a disappointment. It looks similar to zucchini, grows well and other than some fruit-splitting issues, it is impervious to insects and disease here in South Florida (unlike zucchini). So there's that.
It tastes like a cross between cucumber and zucchini. I like cucumber and zucchini, and this would be a good trait if it tasted like zucchini when cooked and cucumber when raw. Unfortunately, it tastes like zucchini (without the pleasant nutty overtones) when raw and it tastes like cooked cucumber when cooked.
It could have value as a filler vegetable in casseroles, blended and heavily seasoned/sauced.
The other negative is that you have a narrow window to harvest luffa for eating. It quickly gets oversized and spongy.