README.md in excel-esv-2.0.0 vs README.md in excel-esv-3.0.0

- old
+ new
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 # ESV
 
 Ruby library/gem for Excel parsing and generation with the ease of CSV.
 
-Exporting CSVs because Excel generation is too complex? No more!
+Exporting CSVs because Excel generation is too complex? No more! CSVs can also be difficult to open correctly, e.g. in Excel on Mac.
 
-CSVs can be difficult to open correctly, e.g. in Excel on Mac.
+ESV will read and generate XLS files. There is currently no XLSX support, but Pull Requests are welcome.
+
+By design, ESV only reads and writes simple values like integers, floats, strings and dates/datetimes. When parsing a spreadsheet with formulas, you will get their last value, if known.
 
 
 ## Usage
 
 ### Generate data