[kwantam]

One obvious advantage is that it's cheap enough to use as-is. One of the things that keeps me from caring much about Arduino is that it's too expensive to use for anything but experimentation: if I'm building more than a one-off, I'll always do a custom PCB.

For reasonable volumes that's still probably the best approach, but at $8 a pop this is perfect for throwing together some quick project.

By way of analogy: to me, an Arduino is a breadboard. If I use one at all, it's to play with a first concept, and certainly not for any kind of permanent use. If that's true, then this is kind of like solderable perfboard: not optimal, but good enough for many things.