Some quotes from the article regarding that (2 separate quotes; there was text between them):
"To make changes to the photo, you have to use commands located in two places."
"In iPhoto the same option is not so easy to find. If you click the Edit button and look on the Quick Fixes tab, you’ll find a Rotate button. But clicking it rotates the selected photo (or photos) counterclockwise only. If you guess that Rotate options are on the Edit menu, you’d be wrong. Instead, you have to look on the Photos menu, which is where the Rotate Clockwise option appears.
In Windows Live Photo Gallery, just about every task and command is available from the ribbon. The design allows you to pick a tab and then scan its contents to see commands that apply to the task you’re trying to accomplish. In iPhoto, you have to learn where each command lives.
A good example is the option to use the current photo as your desktop background. In Windows Live Photo Gallery you’ll find a Set As Desktop button at the left of the Create tab, or you can right-click on a photo and choose Set Desktop Background. In iPhoto, that option isn’t available on a right-click menu. Confusingly, it’s not available from the menu that pops up when you click the Share button at the bottom of the window; you have to use the pull-down Share menu instead."
> And if you're on new-enough hardware to have real multitouch (the past what, 4 years?), they've already seen the gestural approach because it's been pushed at them from every angle multiple times - rotate 2 fingers = rotate picture. And that works from the editing perspective, the single-picture, and the bunch-o-pictures list. Zero clicks!, since they seem so focused on clicks as a measure of UI design.
Using the multitouch gestures is not quite that obvious. I've used mac for a little over a year and I've never used any other gestures than the two-finger scrolling. Besides, clicking on a single button is just simpler than rotating your fingers (assuming you want to rotate the image 90 degrees).