All in all, it's quite a great cable. Flat and unobtrusive, and can potentially help you save a lot of space. The only downside (and this is a significant one for me) is one that I didn't notice when first ordering them:
When plugged into most MIDI keyboards, the cable itself is angled 90 degrees left or right, not up or down. This means that if you have any other jacks or plugs immediately to the left or right of your MIDI ports, they will potentially be rendered unusable by this cable.
If you have plenty of space to the left and right of your MIDI ports, this shouldn't be an issue for you.
If Rockboard could make other versions of this with the cables angled differently, I would be much more likely to buy more.