While Steve Jobs hated the stylus and worked hard to make the iPhone completely usable without one, in some circumstances you simply need a more traditional way to interact with the iPhone — and the Apple Pencil only works (so far) with the iPad Pro.
Typically, I like using a stylus in cold weather when taking off my gloves would just be too cold. Or sometimes my hands are dirty or wet, and I don't want to touch the screen. In my day job, I often take credit cards via Square, and customers feel more comfortable signing with a traditional writing device rather then their finger. My female friends tell me a stylus is indispensable when you've got long nails because the touchscreen isn't always friendly for those with long or manicured nails.
The $19.99 NuScribe stylus is a great writing instrument in and of itself. Sleek and simple, it has the right amount of weight to hold it comfortably in your hand. As a stylus, it just feels natural. The NuScribe feels just like a pen -- and because it's a pen and a stylus, I use it everywhere. I've got a pen when I need to write and a stylus when I need to use my iPhone.
Since the ball point is on the opposite end of the stylus nib, it's unlikely you'll accidentally use the pen portion on your iPhone screen. I remember my Palm stylus had pen marks for when I pressed the wrong button on my stylus/pen combo.
The stylus nib is always exposed, so in a purse or pocket you have to be careful it doesn't get damaged. Ideally, it would have some protection, but that protection would probably detract from its ease of use.
The price of the stylus is inexpensive enough that if you lose your pen (or it walks off your desk), it won't set you back too far. And, yes, it works great with Draw Something!
Overall, it's a great multifunction stylus that lets bridges your digital and analog world at a price that won't need a carrier subsidy.