The pen is good but there is nowhere on the cover that will allow it to be 'docked' but my review is solely concerned with the cover.
The cover is robust, thick and of good quality and my Moto G fits within it perfectly. The magnetic flap clicks into place and secures itself without a problem. I have not taken my phone out of the cover since I bought it and have made calls, taken photos and, of course, used it for all the usual internet-based activity.
Even without the pen, I would highly recommend it.