And IFERROR() wasn't added until Excel 2007. The other way to make that operation less unwieldy if the expression was complicated, to avoid repeating it I'd put that inside another cell, and that way it would be =IF(ISERROR(C2),0,C2), but IFERROR is a much better solution.

Excel is such a good tool in many ways, and such a bad tool in many ways. Really experienced power users can follow Excel formulas much easier than blocks of imperative code. But the more complicated it gets, the harder it can be to follow it all. But that also goes the same for software, too. I do think that there is something powerful about the "debugging" you always have turned on in Excel, in that you always know what value a formula has produced, even after it has run. And you can (usually) easily see at what point an error started in your calculations.

For the programmers out there who aren't fans of Excel, or aren't super familiar with it, if you haven't seen "You Suck at Excel with Joel Spolsky" [0] you might be pretty amazed at what you can do with Excel at an intermediate/advanced level.

[0] https://www.youtube.com/watch?v=0nbkaYsR94c