If the functional programming language requires that each expression must be exactly one line with no comments, I'll pass thanks. Long Excel formulas make Regex look like poetry.
If you have a long expression, you can break it into multiple ones by storing some intermediate results in another cell. You can also hide such cells or put them in another sheet.
This might sound like a hack, but being able to see intermediate results makes debugging complex expressions easier too, so in a sense it is working as intended.
Formula -> Trace Dependencies/Precedents is also super handy! I have a short VBA loop that applies it to all selected cells. It makes it very easy to visually spot one cell reference that's wrong, because 20 cells connect to corresponding cells with parallel lines, then one isn't parallel.
Ctrl+Tilda toggles show/hide formulas, which helps identify input cells when you inherit a messy spreadsheet.
This is a big one, especially if your edition isn't English/US.
Also the number formats and locale settings can cause quite a bit of trouble, if its not English/US. Alot of data warehouse setups output files with U.S formats even in Europe.
On longer formulas, I do Alt+Enter while editing the formula to get a new line, then 4 spaces for an indentation. Just like that, you can keep track of start/end parenthesis.
It's not perfect, I wish it would automatically format that way, but it certainly makes maintenance easier.
