Take any idea of what you think is a tiny pen and throw it out the window. The Ohto Minimo Ballpoint trumps them all, even claiming it is the world's thinnest ballpoint. After using it I have no disagreement with that statement.
This is the first mini pen I have used where I couldn't use my normal tripod-style grip (index finger and thumb on front, backed by my middle finger). It has been close with other pens like the Zebra T3 but I could always get there. With the Ohto Minimo I could only grip it between my thumb and index finger to write with. This was a problem at first but I adjusted quickly and got decent writing performance.
With a pen this small comfort isn't necessarily the priority - vanishing into any notebook, pocket, or purse is. In fact, Ohto packaged this pen with its own credit card sized holder so you can keep tabs on it. That's a hint folks.
The Minimo is too small for me to get any regular use out of. My choices in the mini pen arena are downright gargantuan comparitively, but I'll stick with the Monteverde Poquito or the Pentel Slicci Techo for my mini needs.
(JetPens is an advertiser on The Pen Addict and I received this product at no charge.)