I use mine in lieu of a smartphone, I suppose. I wanted something portable, and a full-fledged computer served my needs better than any smartphone could have. It goes everywhere I go (I bought it because it was small enough to throw into my flight bag and take with me), and I keep track of my schedule and emails on the go. I use it for flight-related activities (checking weather, filing flight plans), business-related activities (keeping track of reservations, typing invoices), and hobby-related activities (amateur radio stuff, some old console emulators).
What a great little machine. I'm glad I got one before they were discontinued.