Nearly five months after Google Inc. bought a Massachusetts flight-information software company, the Internet giant has unleased the fruits of that $700-million purchase. Google\'\'s airfare search tool was unveiled last week , offering what Google says is a faster, more flexible online tool for finding the lowest fare between two locations. The reviews so far have been mixed, but Google says it plans to upgrade the site soon, reported the Los Angeles Times newspaper. Critics point out that the tool found at http://www.google.com/flights shows only domestic, round-trip, economy-class fares, making it ideal for leisure travelers. They also note that flights to many small cities are not yet included. Unlike a few sites that block out select airlines, the Google site shows prices for all carriers and allows travelers to filter flights by price, number of stops and duration. Other features on the site let travelers see ticket prices over a span of dates and from several airports in a region at the same time. But none of this is groundbreaking. The travel website Kayak, for example, offers many of the same features, including a map of the region showing the prices of airline tickets to nearby destinations. The big advantage of the Google site is its speed. \"It\'\'s almost instantaneous,\" said Ed Perkins, a contributing editor for the website Smarter Travel. For now, he said, the site won\'\'t be very popular with business travelers, who typically want a selection of seat classes and don\'\'t have much flexibility in their flying schedules.