Yes! You can add your own message (and logo, if you choose) that will be added to each packing slip! Do this by going to Stores → Edit.
You can also include a personalized message on the packing slip when submitting a manual or integration order by checking "Include a custom note" on the review page. Order prices will be hidden from packing slips with a gift message for US domestic shipments and shipments within the EU from our Europe location.