I don't know if this is a problem anywhere, but something I wanted to mention and see if anyone knew a reason for it.
If I have a simple formula for copying a cell, just "A1", then Cell.Value is the actual value in A1. If I do anything to that value, like "A1+0" then Cell.Value becomes the formula.
I've looked at the discussions surrounding calculating results of formulas (count me as another looking forward to that feature), and I'm okay with just using Cell.ValueCached for that and dealing with the limitations of when and how that gets updated.
My problem is when that original value in A1 is a DateTime (haven't looked for other data types or formatting to see if others share this behavior). In the both simple and complex cases above, the ValueCached is the integer representation instead of the
formatted value, so I see "40816" instead of "9/30/2011". This just makes it harder to always pull the ValueCached when a formula is defined.
I'm guessing that this is Excel's doing and nothing ClosedXML is responsible for. I just thought the behavior was odd.