If you like big, fat pencils then this is the one for you. I've never been a person to gravitate towards the thin or skinny writing implements, and this is the most comfortable pencil I've ever used.
My fourth grade teacher told me that I hold my pencil differently than most people do; I rest the end of it on my ring finger and put my index and middle fingers along the side and top of the pencil. I don't know if this is why I prefer bigger pens and pencils, but this one is perfect for me because it has a big round rubber grip that tapers at the end and takes up about a third of the pencil.
It also has a long eraser that lasts forever. When you wind it out all the way it's about a half of an inch long, and it's the best eraser I've ever used. It never smears the writing, and I've never torn paper with it either. It also doesn't leave those annoying eraser crumbs, but instead your mistakes roll up into little sticks that are easy to wipe away.
From what I've seen, this pencil is available in 0.5 mm and 0.7 mm lead sizes. You can store a lot of lead in this pencil, which is great because you're not constantly refilling it (or running out of lead) if you write a lot with it. Papermate used to manufacture the Ph.D. mechanical pencil in a dark green, a dark blue, a copper brown color, and a red color, but lately they've gone to pastels (which I love!). I have this pencil in a periwinkle blue color and also in a lavender purple. I think they have pastel greens and pinks as well. The metal color is silver, which goes well with the pastels, while the grip is clear and textured.
Some of my oldest pencils of this brand date back to high school for me, so they are well over ten years old and still working well. There is also a ballpoint pen version, so of course I have matching pens and pencils. You may pay a little bit more for this pencil, but it's a good investment that will last a long time.