The apps have a familiar interface, with the same Ribbon interface and layout. But at the same time, they're not just a port of the regular desktop version. Menus have been optimised for touch; objects can be dragged, rotated or resized with a swipe, and the interface scales properly in both portrait and landscape mode.
There's solid integration with other iPad features. You can use voice dictation to create a document, perhaps, or AirPlay to project your finished presentation.
You get plenty of functionality, too. This isn't the hobbled Office Mobile for iPhone: there are templates, tables, footnotes, filters, charts, transitions and just about everything else you'll need. Everything is very configurable, formatting is preserved so documents look just as you'd expect, and of course you can save and share your documents in OneDrive, OneDrive for Business and SharePoint.
If you're just looking for a viewer, then the good news is that the Office apps are free. Just download them and you'll be able to read and present documents, spreadsheets and presentations.
To create or edit documents, though, you'll need an Office 365 subscription. If you have one already, no problem; you're covered for all the apps installed on a single tablet in addition to your PC if you have an Office 365 Personal subscription ($6.99 a month) or on up to five different tablets alongside your five PCs or Macs if you have the Office 365 Home sub ($9.99).
What's new in Microsoft Excel for iPad 1.1:
+Send PDFs: Now you can send Excel files as PDFs.
+Flick to Select: Flick a cell’s selection handle in any direction to quickly and easily select all the data in a row or column.
+External Keyboard Support: Using an external keyboard is even easier. Use the same keys to input data and move around a worksheet as you would on your PC or Mac.
+PivotTables: Interact with PivotTables that have source data in the same workbook.
+Print Options: More paper sizes and scaling options give you more control over the layout when printing your workbooks.
+Picture Tools: Crop to focus on just the right part of the photo, or reset to undo your changes.
+Fonts: Third-party fonts are now available in the Fonts menu.