I've been doing Excel and VBA work for my internship this summer, and I have to say, I have an immense amount of respect for the engineers behind Excel. Excel is incredibly extensible, it has very nice built-in error handling for mangled data (but horrible exception handling in VBA), and overall it is simply a joy working with it.

Sure, it has some pain points, but for my use case (financial analysis), it complements Bloomberg very well. Bloomberg's Excel add-in is very well-engineered, and there is even a way to hook into Bloomberg through VBA. Cheers to the MSFT devs who crafted this stuff.