The Livescribe Sky pen marries old-school pen-and-ink with the cloud. If paper remains a core part of your workflow, this is the best pen of its kind on the market. You can save notes and audio recordings to your Evernote account via Wi-Fi, or you can plug in a Micro-USB cable and save your work to a PC or Mac.
The pen is fairly bulky, but it's pretty comfortable to hold. It would stick out from inside a pocket but it slips easily into a travel bag. The pen cap is easy to lose and hard to put on, so I usually left it off (and the tip didn't suffer from the exposure). Livescribe makes smart use of its tiny LCD screen, displaying Wi-Fi and battery indicators as well as the time and date. Dive deeper and you can play with the display: Use your handwriting and the interactive "buttons" in its supported paper notebooks to play simple games, run equations on a calculator, and translate words. There's even an ecosystem of apps, including dictionaries.
Other smart pens, such as the Adapx Capturx, let you write on any type of paper, but I've found those better for paper-form input versus freehand writing. Livescribe requires special (and pricey) paper, with tiny dots on the page that track your writing with precision.
The Livescribe Sky pen is designed to be paired with Evernote, so it won't be of much interest if you don't use that app. It's a plus, though, if you enjoy Evernote's productivity features (and you get an Evernote Premium account for a year). Use tidy penmanship with your Livescribe pen, and Evernote's optical character recognition can translate that into digital text.
Do you need the Livescribe Sky pen? For most people, that's an easy no. For example, you can always take a picture of handwritten notes from your smartphone and send it to Evernote, so why pay between $120 to $250 for a smart pen? One reason is that Livescribe does cool stuff other devices can't, including syncing audio recordings and written notes. This makes it a great tool for journalists covering events. Students and teachers could benefit, too. An instructor could share "pencasts" that explain trigonometry ratios, for instance, while students take interactive notes to spell out the formulas and shapes during class.
The Sky pen is also more portable than even a tablet with a supported pen. While serious artists will need Wacom-level sensitivity, Livescribe's pen is good enough for casual sketches. Its battery lasted for weeks as long as I remembered to turn it off regularly.
The Livescribe Sky pens cost $170 for 2GB (200 hours recording), $200 for 4GB (400 hours) and $250 for 800GB (800 hours). The Sky pen's wired predecessor, the 2GB Echo smart pen ($120), is also still available. Hook it up to a Mac or a PC, and you can upload notes to Google Drive, Facebook, Evernote and OneNote.