Don't be fooled by the marketing—Numbers has 90% of Excel's core functions; it even had RegEx before Excel did. IMHO, Numbers UI/UX is dramatically better than Excel's.
Of course, it doesn't have Excel's advanced features or access to plugins or to Python scripts. The users who need that know they need Excel… but you can go surprisingly far with Numbers.
Like I originally said, there are some tasks where you absolutely need Excel.
