So Foursquare co-founder Dennis Crowley thinks that Facebook Places is “pretty boring”? That’s the line he took in an interview with the UK’s Daily Telegraph.

“I have now had a chance to play around with Facebook Places and it’s not that great or interesting,” Crowley said. “It’s a pretty boring service, with barely any incentives for users to keep coming back and telling their friends where they are.”

Crowley said he believed Foursquare’s gaming mechanics and the ability to become mayor of a location would keep users engaged. Even if Facebook decided to copy the incentive structure, he said Foursquare was working on a range of new mechanics to keep the site fresh and stave off “check-in fatigue”.

Hmm. It sounds like sour grapes to me, Crowley.

Of all the location-based services on the market, Foursquare has the most to lose from Facebook Places simply because it’s the biggest. Now it faces a new and much larger rival. Facebook has 500 million users worldwide and Foursquare has nearly three million – an imbalance that Crowley admitted was a “little scary”.

Foursquare took a risk in rejecting overtures from Facebook, and more recently Yahoo!, and deciding to go it alone. That risk might pay off handsomely especially if Facebook’s debut into location manages to grow the market. However, if Facebook Places instead siphons off most prospective check-in users, that would choke off the oxygen supply to the rest of the location market and Foursquare’s best days would be behind it.

Crowley might have a point on the gaming mechanics and the importance of built-in incentives to check in. The competitive aspect of Foursquare has been a big factor in its success to date. Yet I have the sense that the game aspect might not be as addictive in the long term as Crowley thinks. Based purely on anecdotal evidence, I believe that eventually people would tire of competing of become mayor of places. The push back from friends who are sick of reading Foursquare updates on Facebook and Twitter could also stymie growth, although of course these options can be deactivated.

Aside from numbers, the key advantage that Facebook Places offers over Foursquare is the social aspect because of the close integration with a site where people already have a critical mass of friends. Places has features such as the ability to tag multiple people with one check-in and a repository for stories and photos associated with a location. This could prove more compelling in the long run than earning points and titles.

Of course, I don’t know what new mechanics Foursquare has up its sleeves, although Crowley hinted at a recommendation service of some kind. I also don’t know what Foursquare’s integration with Places will look like, since the company has had access to the API for a while but is yet to do anything with it. Contrast this with Gowalla, Booyah and Yelp, which all announced integration plans at the Places launch.

Foursquare is far from doomed but there’s a lot at stake for the start-up. Crowley’s words may spring from deep personal conviction, but they are certainly not without context.