After months of waiting the New York Times has finally unveiled the details of its metered paywall. It says it will charge the most frequent users of its site $15 a month.

I think it’s a good price and am betting a lot of readers will be of a similar view and take the paywall plunge.

There is growing evidence the New York Times can succeed as I blogged earlier this week. The New York Times says “it is doing this in in a bet that readers would pay for news they have grown accustomed to getting free”.

The paper says it will begin charging as of March 28 and will allow visitors to read 20 articles a month for free. That is a similar limit to the Financial Times and one that is designed to get its most loyal readers to pay up whilst not driving away the more casual visitors who make up the majority of the its traffic and bring it valuable online advertising revenue.

In addition to the $15 charge, this also gives mobile access, it will offer a $20 charge for web and iPad access. There will also be a  $35 for an all-access plan.

“A few years ago it was almost an article of faith that people would not pay for the content they accessed via the Web,” Arthur Sulzberger Jr., chairman of The New York Times Company, said in his annual State of The Times remarks, which were to be delivered to employees on Thursday morning.

“This move is an investment in our future,” he said. “It will allow us to develop new sources of revenue to support the continuation of our journalistic mission and digital innovation, while maintaining our large and growing audience to support our robust advertising business. And this system is our latest, and best, demonstration of where we believe the future of valued content — be it news, music, games or more — is going.”

Sulzberger stressed the importance of remaining open to the web and not shutting the paper off as The Times has done with its anti-social media approach.

“The challenge now is to put a price on our work without walling ourselves off from the global network, to make sure we continue to engage with the widest possible audience,” Sulzberger said.

The paper said that not all visits to NYTimes.com website would count toward the 20-article limit. In another nod to the social web the New York Times plans to allow those accessing via search engines and social networking sites to access  five-articles a day for free. Also very reasonable.

The first to experience the paywall will be the Canadians. The New York Times says charging the Canada first would “allow the company time to work out any software issues before the system goes live in the United States”.

Some are already saying that the model announced by the NY Times won’t work:

Walter Frick, writing on the Atlantic, argues that by giving those who come via social media so many articles a day the paywall is unsustainable.

“Readers who come to Times articles through links from search, blogs and social media like Facebook and Twitter will be able to read those articles, even if they have reached their monthly reading limit. For some search engines, users will have a daily limit of free links to Times articles.

“This is tantamount to saying that if you’re a power-user, or even just someone heavily immersed in social media and the blogosphere, then the paywall won’t apply to you. Which is basically admitting that a paywall isn’t sustainable.”

Put that way it sounds like there is a huge whole in the New York Times paywall strategy, but those coming via search, blogs and social media are dependent on those who do the sharing.

While that is how we consume some media many of us want to read more than a few articles we see shared via our social web circle. And if you want to see more of the New York Times – enjoy mobile or tablet access — then you will have to subscribe.

It is the growth of that kind of access, I’m sure, will provide a lot of future paywall revenue.

It is essential to have the paper’s content shared socially as it both ensures ad revenue and acts as reminder of what the paper has to offer overall.