When Matthew Wolf first walked around with his new iPhone, he said passers-by would stop him in the middle of the street to take a look at the gleaming, obsidian-colored device.

“It was an exciting thing for people at first,” the 25-year-old independent filmmaker said.

Nearly a month after the device’s launch, however, people no longer stop to admire Mr. Wolf’s phone and he has come to realize that owning the first generation of a new technology comes with not just a hefty price tag, but other costs as well.

“People hear echoes when I call, the home button sticks periodically, and you can’t send group text messages,” Mr. Wolf said. Other complaints include a painfully slow connection to the Internet when the phone is outside a Wi-Fi hot spot, and security concerns.

Apple Inc. launched the iPhone to much fanfare, but sales have been sluggish. According to numbers released yesterday by the phone’s exclusive carrier, AT&T, 146,000 iPhone accounts were activated in the first 30 hours that the product was available. Market observers were expecting far higher numbers, with analyst Gene Munster of Piper Jaffray & Co., for example, estimating that as many as 500,000 buyers would pick up the new gadget.

“The demand for the iPhone has seen a significant decline in the past 10 days,” a CIBC World Markets report published yesterday said. It conducted a survey of Apple stores nationwide, finding “decent inventories at stores, and thin demand at best.”

On news of the sluggish iPhone sales, Apple’s stock price slid 6%, to $134.89, at the close of trading yesterday. Despite healthy subscriber growth shown in the earnings statement, AT&T’s stock price slid 1.27%, to $39.68.

To combat the slow sales, analysts are predicting that Apple will step up its marketing efforts and release new versions of the phone early to compensate for the loss of momentum.

Not everyone is unhappy with the results of the iPhone. “Virtually all our stores sold out during the first 90 minutes” the phone went on sale, and sold out again on day two, an AT&T spokesman, Michael Coe, said. “Demand has remained strong and more than 40% of activations were not previously AT&T customers.” He added that the drop in AT&T’s stock was part of a larger overall stalling out of Wall Street yesterday, and was less than the 1.6% decline of the Dow Industrials.

Representatives of Apple and AT&T would not give sales figures for iPhones, but an Appleinsider.com report on Monday said the city’s two Apple stores took in $68 million in total sales during the second quarter. The Fifth Avenue store had a 15% increase in sales compared with the same quarter of 2006, while the SoHo store declined by about 17%, the report said.

Still, at the AT&T store at 82 Wall Street yesterday, several people were shopping for new phones — but many were opting for Blackberries and Sidekicks.

“I never buy the first product when it first comes out — there are too many kinks,” a structured financial analyst who lives in Queens, Andy Yan, 37, said. He said he couldn’t even use the iPhone if he wanted to because his company’s e-mail server doesn’t support it.

A chef living on the Lower East Side, Jared Gadbaw, 28, said he was planning to buy a Samsung Blackjack because, with rebates, he would only have to pay about $100. He also said he wouldn’t have to change service providers.

“It’s not really worth it to me,” he said, adding that the iPhone he saw wasn’t as user-friendly as he expected. “It’s not as easy as I thought it was to navigate. It’s not as easy as the commercials make it look.”

Making matters worse, the firm Independent Security Evaluators announced yesterday its researchers had developed a way to take complete control of any iPhone by directing it to a Web site embedded with code. The security loophole allows a second party to download a person’s text messages and telephone numbers onto another computer, according to the group’s security briefing.

Apple officials said they take all security threats seriously and were reviewing the group’s “hack.”