State of the Art: Microsoft Office for the iPhone Is Here. Yawn.

Office for iPhone is big news, but not because the software is earthshaking. No, it’s a big deal primarily because of the politics of the situation — the optics, as public relations people say.

Here is Microsoft — the once-mighty software global overlord, years into its repeated failures to produce a successful smartphone — creating an app that lets you edit Word, Excel and PowerPoint files on the gadget that defeated it, the iPhone. It’s as if somewhere along the line, Microsoft executives started wearing “If you can’t beat ‘em, join ‘em” T-shirts.

Microsoft, of course, doesn’t see it that way. The company reports tiny but measurable upticks in sales of its own Windows Phone (which actually is a terrific phone). So why, then, did Microsoft create Office Mobile for the iPhone?

Here’s a hint: You can’t buy the Office Mobile app outright. It’s free with your paid subscription to Microsoft’s Office 365 plan, which costs $100 a year. It’s a service that lets you download Word, Excel and PowerPoint to up to five Mac or Windows computers.

Since Office 365 arrived, Microsoft has been busily trying to sweeten the offer. Office 365 membership gets you one hour of free phone calls a month using Skype. It also gives you 20 extra gigabytes of storage on the SkyDrive, an online hard drive for backing up or transferring documents. (Nonsubscribers get 7 gigabytes free.)

And now it gets you this app for iPhone (iPhone 4 and later) and iPod Touch (5 or later). That’s why its impressively clunky full name is Office Mobile for Office 365 Subscribers. (Office Mobile is already available on Windows Phones, and doesn’t require any subscription.)

You can run the app on up to five iPhones. If you ever stop paying for your Office 365 membership, the app stops working. Your documents are safe in that case, however. They’re both on your phone (until you delete the app) and on your free SkyDrive.

To use the app, you enter your Office 365 name and password. Once you’ve signed in, you see a list of all the Word, Excel and PowerPoint files that you’ve stashed on your SkyDrive. When you select a document’s name, it rapidly downloads to your phone, and you can work on it without an Internet connection. Next time you’re online, the changes get sent back to the SkyDrive original. You can also use Office Mobile to edit documents that people sent to you as attachments in the iPhone’s Mail app.

But once you tap a document to open it, you quickly discover that this app isn’t anything like the full Microsoft Office — it’s more like the Microsoft Vestibule. It’s extremely stripped down. It offers only the features Microsoft thinks you’ll realistically use on a bus or in the doctor’s office with nothing but your phone in hand.

The miniature Word module, for example, offers comments, outline view, bold/italic/underline/strikethrough styles, font and background colors and highlighting. You type, cut, copy and paste using variations on the iPhone’s standard finger gestures. And when you open a Word document, it jumps to the spot where you were last reading on your computer. Slick.

Notably absent: style sheets (normal, heading 1 and so on). Spelling checker. An undo command. The ability to change the font or insert a graphic. You can make the type bigger or smaller, but you can’t specify a size by number. Layout-intensive documents — lots of boxes, embedded graphics and so on — sometimes don’t come through to the phone fully intact.

The Excel module is by far the most fully featured app. It displays most elements of a spreadsheet, including charts and graphics. You can scroll around with your finger, zoom in or out with two fingers, lock a row or a column so it doesn’t scroll, rotate the phone for a wider view, edit comments, flip into outline view, edit formulas, create graphs, change numbers, sort, find, filter and format text and numbers. If the sheet has multiple pages, you can switch among using bottom edge tabs, exactly as on a computer. There’s an undo command. (Why here, and not in Word?)

Notably absent: you can’t rearrange rows or columns (although you can adjust row heights and column widths), and you can’t insert new ones.