Once you got used to it, honestly not really, other than needing Excel (not a huge deal since it was a Windows only application). I've no idea what the config parsing code looked like, but with the right library I doubt it was worse than any other non-trivial config parsing code. Mainly it just felt very wrong to my Unix, everything must be a text file, brain.
Never thought I'd get a chance to tell this story.
Early 1990s, college internship. The company did presentations for clients, like many do. They had an unusual way of presenting data that required using actual protractors to draw circles and curves, with pencil, on otherwise computer-generated charts. They read numbers from Excel spreadsheets and plotted them on paper.
I was shocked, to say the least. I proposed writing a program that read Excel spreadsheets and emitted the graphics. They loved the idea, especially from a summer intern.
So I wrote a letter to Microsoft asking for documentation of the Excel file format. A week later I got a thick envelope with a photocopied manual completely describing the format. I remember the word BIFF throughout. I wrote the program, it worked great, and I even negotiated a hefty lump-sum payment to sell it to them at the end of the summer.
It left me with a very positive impression of Microsoft as a developer-friendly company. Makes sense; developers are their platform's customers, and they're good at serving their customers.
There are some pretty awesome libraries for reading and working with Excel files - Aspose.Cells being one I used for years - basically a headless re-implementation of most of Excel usable via an API.
