In the unglamorous world of financial data and business news, Bloomberg is the closest thing to an Apple or a Google—an eccentric innovator that plays by its own rules, bringing imaginative and useful products to market.

But with those products can come features that exasperate even the most devoted customers. For owners of the sleek and addictive iPod, for example, that means having to use a proprietary cable to download music or charge the device. If you lose that cable, you’re stuck—at least until you can make it to an Apple store or order one from Apple’s website. Users of Google’s fast and functional email service had to wait almost two years for the search-engine giant to add a Delete button. And people who rely on Bloomberg’s data terminals have to deal with an interface that’s a throwback to MS-DOS.

Dreamed up by the current mayor of New York, Mike Bloomberg, after he got booted from Salomon Brothers in 1981, the Bloomberg terminal is used by traders, analysts, government officials—even the Vatican—to get real-time information on everything from plain old stocks and bonds to currencies and derivative products. The system also allows users to chart historical prices, read news, and communicate with other Bloomberg users around the world. More than 300,000 people use the terminals, which are so distinctive that the 2004 model, created by Antenna Design, even made it into the Cooper-Hewitt National Design Museum. That souped-up black box—available only to customers who subscribe to the Bloomberg Professional Service, which costs up to $1,800 per month—has adjustable monitors, a fingerprint scanner, and a microphone for speaking to other users.

But, oh, those screens.

“It’s a great machine, in that it has information you can’t get elsewhere, but it hasn’t improved its interface in the past five years,” says a private equity associate in Chicago who regularly uses a terminal to check interest rates and historical prices. “It’s hideous.”

The main problem is its use of color, says Elliott Malkin, an information architect in the design group at NYTimes.com. The Bloomberg system is customizable, so no setup is the same. But a typical screen teems with charts and tables drawn in blue, yellow, and orange on a black background, creating a certain nightmarish quality. “The color should be used to make the screens easy to parse,” Malkin says, “to help the user break the screen up into digestible compartments of information.”

What’s a little beauty when millions of dollars are at stake? A well-designed interface can improve productivity, says Jakob Nielsen, co-founder of Nielsen Norman Group, a research firm in Fremont, California. A 2003 study he conducted found that when websites were redesigned to make them easier to use, their companies’ sales increased by 100 percent and productivity went up by 161 percent. While website and terminal design are not perfectly analogous, the results hint that Bloomberg has everything to gain from revamping its terminal’s look and feel.

In the case of Bloomberg, Nielsen says terminal designers made the right choice by allowing users to create screens that are basically huge data dumps featuring row upon row of numbers and text. “The human eye is extremely fast in moving across a screen, which makes all the difference in a world where a second can mean $1 million,” he says.

Still, he sees many improvements to make. Like Malkin, Nielsen points to the use of color, suggesting that dark text on a light background is easier on the eyes than the reverse. (On the Web, Bloomberg has decided to use black text on a white background for its news stories.) Increasing the contrast and using higher-resolution text and graphs would also improve readability.

Bloomberg maintains that it is constantly updating the terminal, as Mike Bloomberg notes in his 1997 autobiography: “While our competitors are still sucking their thumbs trying to make the design perfect, we’re already on prototype version No. 5. By the time our rivals are ready with wires and screws, we are on version No. 10.” But a decentralized process for implementing software updates still caused problems. Programmers and designers could make changes to software independently of one another, creating variations across different pages, says Raquel Tudela, a graphics designer at Bloomberg. To achieve consistency, the company has created a style guide for visual elements such as colors, buttons, and menus.

So far the drab look probably hasn’t hurt Bloomberg’s bottom line. The competition—terminals from Thomson and Reuters (which Thomson just agreed to buy)—isn’t any prettier to look at. So Bloomberg isn’t looking to do a major overhaul of its terminals’ graphic design anytime soon. In fact, company executives see the Bloomberg terminal’s unique presentation as a status symbol and a selling point.

“We have to be religiously consistent” to satisfy users who become attached to terminal’s look and feel, says Bloomberg chief executive Lex Fenwick. “You can see a Bloomberg from a mile away.”