This is so far the smoothest writing ballpoint I've found. Not surprising considering its 1.6 mm ball (which writes a 0.55 mm line).
In fact, it's smoother than most gels. And in addition to that, it lays down a rather good line. I'd like to fit this refill in a retractible pen to use instead of some of the gels I use now. If you like smooth writing, I recommend you try this one.
One possible problem with it is that if you carry it point down, ink may gather on the ball, so when you start to write it may cause a blob on the paper.
And for a sort of thin disposable pen, it's got a quite comfortable grip with three evenly spaced ribbed surfaces, which happen to fit where I put my fingers.
I like to put the refill into other pens.
A Pilot ballpoint pens page.