I'm looking at ordering an Adafruit motor shield, but would like to make sure that the I/O pins are still accessible through the shield. Can anyone confirm?
Based on the picture:
It doesn't look like it brings out the pins. Theoretically, you could use extra - long female headers to bring out the pins and connect it to the board. I don't know which pins this shield uses, nor do I own it, so I can't say for sure.
If you buy it in kit form, you can assemble it with stackable headers, or male headers that are long on both ends, to get easier access to the I/O pins. There's an area of pads for the analog pins that makes them more convenient to use (it has sets of 3 pads, with extra +5 and ground pads next to each analog input. Especially handy for hooking up pots).
A word of caution, though: the motor functions use up almost all the digital pins (10, to be specific). If you need lots of I/O pins for your project, yo may want to get one of the external motor control boards with a serial interface.
as explained on the page of the shield, pin 2 is free you can access on the shield. pin 13 is also not used.
all analog pins are free, they can also be used as digital pin (14-19)