I've only seen this in seed catalogs (I'm looking at Johnny's right now), never tasted it or seen it in the market. What does it taste like? Do you cook it like other greens, as in chard or bok choy? Is it good raw? Do you prefer green or red? Does it really vine like a cucumber or like a pole bean? Does it have other names?
I grew red malabar spinach in my very first veggie garden this year. Here's what I've noted: it's spinach-lite. The flavor isn't as hearty, the texture of the leaf is a little different as a substution in a pasta salad I make: Spinach will remain in tact in the salad for a few days; malabar spinach will be great at first but start to break down and achieve a very undesirable texture as left overs. However, it is ridiculuously easy to grow, pest and disease resistant, grows fast, and is very, very attractive. It's a great addition to salads and stir-fry, so I do recommend growing it. It's vines like pole beans and grows fast, so it's a great space saver in a small garden on a trellis or garden arch. Bottom line: Grow some but don't expect a 1:1 replacement for regular spinach.