How long I've had it: I've had it for 5 years total, (when the keyboard released) but ended up buying a replacement maybe 3 years into owning the first one.
Price I originally bought it for: $80. Price has stayed about the same. I don't expect you'll find it much cheaper.
What exactly I do with it: Everything. It's the only keyboard I've used for the past 5 years. Before that I went through maybe 3 within a year. I really LOVE Logitech. This keyboard specifically.
Brief summary listing some pros and cons (unless there are no cons): It's Logitech keyboard setup program and the keyboard itself are very user friendly. It's also very quiet for a mechanical keyboard. There's not much to it, honestly, but it's everything a typical PC user needs.
Overall rating (1-10, 1-5, F-A, whatever scale you want to use to rate it): 8/10 Good enough for me to buy it twice.
(sorry it's a little dirty)