Not bad advice at all; while anecdotal, I learned to write properly using a fountain pen - my grandfather handed me one as I started primary school, claiming that this would learn me how to write properly, doubly so as I am a leftie.

It took a while, but I believe he was right - as the fountain pen forced me to write slower and more deliberately, it did improve my handwriting.

(I still (35 years later) mostly write with a fountain pen, always carrying my grandfather's Souverän 400 in my shirt pocket - it was gifted to me once I had learned to write properly.)