While the colours and such do look very nice, the "writing samples" images show exactly why I hate using fountain pens. I'm left-handed, so if I try to write prose then my hand will just smudge the writing. I've always found that cheap ballpoints are the least likely to smudge, even if they still leave residue on my hand, and as the pen gets more "premium", the worse the smudging problem gets.

I like to use as fine a pen as possible if I'm just trying to work something out (diagrams, small notes, etc), and I've found that a Unipin Fine Line (currently a 0.03) does work well, though I've been having some issues with ink flow recently (though the pen is probably nearing the end of its life at this point anyway). I have liked the feel of Uniball Eye pens in the past, though they have a similar smudging problem if used for prose. Other than that, the cheapest Bic ballpoints have been the most successful for me, since the ink dries super fast and they feel good enough to write with.

In school I was given a specific left handed fountain pen to write with, but I always had to write at wonky angles to try and keep it legible, and it never really worked very well anyway. Pushing the pen instead of pulling it generally gives bad results. I have experimented with trying to do mirror writing, like Leonardo da Vinci, but obviously nobody else can read it like that