Earl, I'm just a tad older than you, and a math teacher at middle school level.
It's somewhat of a misnomer to call the NSpire CX series a "calculator." It's really more of a "student mathematical experimenting or learning device." Truthfully, it's more of a PC than a true calculator, containing "apps" for calculator, graphs, geometry, lists/spreadsheet, data/statistics, and notes. A variable or function defined in one app is accessible in the other apps, so, for example, you could use the calculator app to define a function like f1(x)=3x2+7 and use that function in the spreadsheet or, of course, graph app. So it's kind of dynamic. In it's latest iteration, like the Casio Prizm, you can draw or import a picture of something, select some points along a line or curve on the object, and have it derive the equation. That's kind of neat for students discovering math principles, but not terribly useful for an engineer, for example, I think. Or you can dynamically change the shape of a graphed curve (by pointing and dragging) and see how the related equation changes in realtime. If these types of things interest you, you may find it worthwhile. If you're just looking for an engineer's calculator, you probably won't like it.
It's color screen is fantastic, but at my age the letters are a tad on the small size.
And it's not cheap.
