There are both aesthetic and performance benefits from using the latest and greatest in CSS. Aesthetically, the transition between map levels is more pleasing due to a fade animation. For performance, some webkit and mobile browsers use hardware acceleration when a webpage uses CSS transforms. This is especially beneficial on older versions of iOS.
Like other new HTML5 and CSS3 capabilities, transforms are not yet consistently implemented across browsers. For a complete rundown of browser support, check out caniuse.com’s browser support chart for CSS3 transforms. While that’s a good reference, there are some subtleties to the current implementations. In Chrome on XP, there’s an existing bug that will hopefully be addressed by Chrome 17 in early 2012. For Firefox, version 10 (also due in early 2012) should bring full support for transforms.