The obvious part first: while it's called a pen it does not allow you to write, it just has the same form-factor. Nowhere on the store page does it say that it can write, but I originally thought it would be a functioning pen as well. Perhaps there are third-party pen refills in bit shape you can find elsewhere.
It holds 6 double-sided bits which is great. It's good value for the price and easy to carry due to its factor. It's a bit annoying to take out the bits if you don't have long fingernails, but it's functional enough and very compact.
There's a small magnet at the top. It's just strong enough to hang the screwdriver from a horizontal metal surface or pick up a ****.
The screwdriver comes with a little metal clip so you can attach it on your shirt or something, but it scratches the paint/coating and spins around annoyingly. I removed mine immediately (it comes off easily) since I don't use it, but it left some scratches on the pen's body which is a shame.
After a few days of light use, the end cap came off which I had to re-attach with some superglue. Not sure if this is common, but it seemed like it was just friction-fitted so I assume I won't be the only one this happens to.