Further investigation reveals 30 new options for the design of your Gmail interface, with the original "classic" design available as option #31. Now, I'm not against change—in fact I embrace it—and I think customization is a great thing, but Gmail's Theme debut has me questioning their design sense.
I began exploring my options with the simplest themes–ones that merely change the color of the template and lettering without adding too many crazy details. While none of them are terribly offensive, all of them change the opacity of the lettering such that it's a strain on the eyes to read the text of my already-read emails. I moved on to the themes that seemed to have bolder colors and higher contrast, only to discover that these choices—with names like "Phantasea," "Bubblegum," and Zoozimps"—could be the graphic cousins of Trapper Keeper patterns from the late 1980s. I'm somewhat aghast that with their super-solid cachet among the cultural creative set, Google didn't pull in some graphic design talent to make their new themes match the level of design-consciousness among their users. I can appreciate a little bit of retro, back-to-school flavor, but from "Summer Ocean" to "Bus Stop" there's not a single choice that seems fit for the typical Gmail user.
I've been using Gmail for more than four years and I love it. It's got excellent functionality, it keeps me organized, and I never worry about capacity limitations. Because it's a brand I associate with forward-thinking products and the ability to predict and set trends, I would expect more from a new visual identity. For now I have to stick with the Classic—but not for fear of change—I'll await the day a new array of options become available and I'll try each one.