Instapaper is a fabulous application for the iPhone or iPod touch--truly first rate. As one who reads a lot online and off, I've quickly come to appreciate Instapaper as one of my favorite apps. It's so easy to use, in fact, it's tough to resist saving articles for later as just for excuse to whip out the phone and read something. Drives my wife and kids crazy.

But Instapaper is expensive. One feature--and only one--justifies the US$10 price tag on Instapaper, and that is the ability to download stories to the iPhone or iPod touch and read them anytime, anywhere, with or without a Wi-Fi connection or a cell phone signal.

Instapaper Pro has that feature. Trouble is, so does Instapaper Free. While there are some key differences between the two versions, the app's basic form and function is exactly the same in both.

Instapaper is among the easier apps to use. First, sign up for an account at Instapaper's Web site. This takes all of two minutes. Then you simply add a "Read Later" tab to your Web browser and click it anytime you want to read an article later. (Note: Take care to save the one-page or print screen view of the article you want to read; if you happen to save the first page of an article and you want to read it offline, you will only be able to read the page you saved.) Then when you launch the Instapaper app, simply tap the update button and the stories you saved will download on to the phone.

... as does Instapaper Pro, which adds a tilt screen feature for scrolling through text and the ability to display customized fonts and text sizes.

The question, then, is what makes the $10 version of the app a good buy? Readability and convenience, mostly.

Instapaper Pro features a nifty tilt screen feature that lets you scroll text without touching the screen. If the tilt feature proves distracting, not too worry: You can turn it on and off with the touch of a button. Instapaper Pro will also mark your place so that if you need to click away, you will return to the exact spot in the text where you left off. The Pro version also displays customized fonts and text sizes, and gives you the option of black text on a plain white background or white text on black. You can also open articles in Safari.

Although every one of those exclusive features adds value to Instapaper Pro, their absence does not detract from Instapaper Free. The interface is still a snap to use on the free version. The stories remain highly legible.

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