PHOENIX — Among the many detractors — and they were multitudinous — who thought a light rail line in this sprawling city would be a riderless $1 billion failure was Starlee Rhoades, the spokeswoman for the Goldwater Institute, a vocal critic of the rail’s expense. “I’ve taken it,” Ms. Rhoades said, slightly sheepishly. “It’s useful.”

She and her colleagues still think the rail is oversubsidized, but in terms of predictions of failure, she said, “We don’t dwell.”

The light rail here, which opened in December, has been a greater success than its proponents thought it would be, but not quite the way they envisioned. Unlike the rest of the country’s public transportation systems, which are used principally by commuters, the 20 miles of light rail here stretching from central Phoenix to Mesa and Tempe is used largely by people going to restaurants, bars, ball games and cultural events downtown.

The rail was projected to attract 26,000 riders per day, but the number is closer to 33,000, boosted in large part by weekend riders. Only 27 percent use the train for work, according to its operator, compared with 60 percent of other public transit users on average nationwide.

In some part thanks to the new system, downtown Phoenix appears to be one of the few bright spots in an otherwise economically pummeled city, which like the rest of Arizona has suffered under the crushing slide of the state’s economy. The state, for years almost totally dependent on growth, has one of the deepest budget deficits in the country.

In the first quarter of 2009, downtown Phoenix saw its revenues increase 13 percent, while the rest of the city saw a fall of 16 percent, according to Eric Johnson, a redevelopment program manager for the city’s Community and Economic Development Department. (Businesses along the line suffered greatly during the many years of construction, it should be noted.)

“It is bringing us new customers who didn’t have time to get in the car and drive out here before,” said Joel Miller, a co-owner of Maizies Cafe and Bistro, which sits right along the rail line.

The gaggle of light rail users — including Arizona State University students, who use a line that connects its Tempe campus with the downtown campus — have given a small part of the city a new, dense connectivity that was more or less unheard of in the city two years ago. Pub crawls along the light rail have become a weekend staple, and restaurants have seen new customers from outside the neighborhood popping in off the line for brunch on the weekends.

“I think the biggest impact of the light rail is less tangible,” said Matt Poolin, owner of Matt’s Big Breakfast, a busy spot along the line, “which is that it really improves the image and perception of Phoenix’s downtown, which, although experiencing a significant renaissance in recent years, still is undergoing many improvements and changes. The light rail, largely because it is so well run and nicely appointed, is something that I think most people are really proud of and feel positive about. It is rare to hear anyone complain, despite all of the controversy.”

The controversy was largely attached to the rail line’s cost — $1.4 billion — and the relatively low ticket price — $1.75 each way, with all-day passes for $3.50 and discounted rates for longer-term passes. In a city with low density, miles of suburban sprawl to the east and west of downtown and a historical lack of passion for public transportation, the rail line, one of the nation’s 36 systems, seemed like a white elephant.

But its development over the last decade coincided with the city’s expansion of the downtown convention center, the rise of the new A.S.U. campus and the booming commercial and residential real estate market that helped fuel the growth of Phoenix, downtown and elsewhere, earlier in the decade. Since 2001, when the tax for the new rail line was approved, there has been about $5 billion in public and private investment — $3.5 billion of it private — around the site of the light rail, the city’s development agency spokesman said.

Valley Metro, the line’s operator, hopes to add 37 miles toward Glendale and northeast Phoenix, breaking ground in 2012 and completing the extensions by 2017.

“We would like to see a financial audit before they expand,” said Ms. Rhoades of the conservative Goldwater Institute, echoing those who have been critical of the expense. “We are also proponents of paying your own way, and we think the light rail remains too subsidized.”

The hooting of an oncoming sleek new train is a sound many in Phoenix are still becoming used to, but it has given the city a distinctly modern feel. “There has been this pent-up demand for downtown Phoenix to grow up,” said Nick Bastian, a real estate agent in the city who has developed a blog devoted to light rail news. “And the light rail has given people an excuse to say let’s go down there and check it out.”