It is a beast of a machine, and one of the best in terms of accuracy and precision. It can handle edge cases in both trig and calculus better than any TI or Sharp scientific calculator on the market, and it is wicked fast. The only thing that kept it from being the perfect scientific calculator was its lack of persistent memory. It has a surprisingly powerful little spreadsheet mode that is completely crippled by the fact that if you power down the calculator, everything is lost. Now that I'm aging and my visual acuity is taking a nosedive, I also find the density of the tiny print above the keys makes it more difficult to use, but it is still one of the first calculators I reach for.
That is not only beautiful, but incredibly interesting as well! It is incredibly similar to the fx-991EX, but it has no solar panel and a couple of additional functions. The fx-991EX does not have the product function (ALPHA + x) in the upper right, simplify (ALPHA + (), MCD (ALPHA + *), MCM (ALPHA + /), int (ALPHA + +), intg (ALPHA + -), PreAns (ALPHA + Ans), and two functions that I don't recognize (ALPHA + FRAC) and (ALPHA + SQRT). There are also some localization changes to the trigonometric functions. What a wonderful find!