It's been an open secret that Google has had a flight-search feature in the works ever since the Web giant purchased ITA Software for its flight-information software last year. Now Google will compete with established sites such as Hipmunk and Kayak.

I took Google Flight Search for a spin, and found a site that looks great but needs a little more work before it can rival specialized flight-search sites.

Good-Looking Site

Google Flight Search’s greatest strength is its looks. As usual, Google has clearly put a lot of time and effort into the visualizations for the site, and the work pays off. When you open Google Flight Search, you see a map of the United States with your departure location set by default to your current city (Flight Search seems to be made for domestic flights only at the moment). You can either choose your destination from a drop-down menu or click on destinations conveniently labeled with the city name and the cheapest round-trip airfare Google can find to get you there and back again.

Kayak offers a similar map. However, whereas Kayak stuffs its map with every possible destination, Google keeps things simple, opting for major airports and likely destinations. In fact, Flight Search seems to take simplicity as its watchword.

The default list of flights that appears when you start a search gets right to the point. It lists airline, price, and takeoff and landing times in a single row for a clearer and more compact view of flights than you’d find on sites like Expedia. And the chart view that Google provides even gives Hipmunk--a site known for its great design--a run for its money.

Not Enough Data?

Even though Google Flight Search looks great, its major drawback at the moment is that it has less data than its competitors do. When I searched for flights from San Francisco to New York on Google, Hipmunk, and Kayak, Google missed a few flights that its competitors found, and it lacked pricing data for entire airlines such as Virgin America.

This may be the first time I’ve had to criticize Google because it didn’t have enough data. At the moment, though Google has created some fantastic visualizations for Flight Search, the incomplete flight database will make it hard for the company to compete. Users want the best airfare value they can find--not the prettiest website.

Flight Search just opened to the public Tuesday, and even the developers admitted in the blog post announcing the new feature that they still have work to do. So Flight Search might have more-complete results in the future. For now, however, if you want to make sure that you get the best deal, you should probably stick with Kayak.