Easy to use on a standard breadboard, tiny size, wide power range and clean signal. The breadboard/size features are obvious. The power range means you can drive this board with a 12-15v wall-wart or from a 5v USB port or even 3.3 volts. The clean signal is important if you're using things like the exixe board the use the SPI bus - noisy power will lead to SPI bus errors. Also, cheaper boards made a noticeable high-frequency whine with lower (e.g., 5v) voltages, but not this board.