I am an Excel user for my work. A vast majority of my work is done on my PC. However, I do send it to my iPad, when I want to see a 'finished' spreadsheet. I use my iPad to check on any errors. I also use the iPad to see how good it works for the client. For example, I create spreadsheets for clients to enter data on specific items. I give them a summary spreadsheet and then I collect all of these spreadsheets from various responders and integrate them into one report spreadsheet. My team has deployed iPads for this purpose. We use Numbers on the iPad. That has worked the best for us as it is pretty much equal to Excel.
Some caveats: 1) Use the same font and font size for both versions (Excel & Numbers) 2) Do not create formulas that require a table of information to calculate a result for the Numbers version. 3) Use simple mathematical equations for column, row or Totals in specific cells, i.e. plus, minus, no multiplications, divisions, or time conversions or data conversions.
Microsoft has not ported its Excel application to the iPad's OS so we have had to resort to alternatives and work arounds. But our data gathering is faster, more efficient, and more accurate. I suppose our work would be even better integrated if we used Apple technology as our computer source. But that would be pretty scandalous to show up at a company plant bearing Apple products and not a PC laptop. Using an iPad took a lot of management review and approval.