I have been a Netapp trainer/consultant for more than fifteen years. I train customers, partners and Netapp engineers on a regular basis. I am based in the Netherlands.
Since I am also a Linux and UNIX fan, I like to work on the command-line. There is nothing wrong with GUI's or BUI's, but to my mind, the CLI gives you more direct control. So I always urge my students to not only work in a graphical interface.
I am certified in Netapp, UNIX, Linux.