I went to see Dave Morin, CEO of Path, because I didn't understand the quirky little photo-sharing service. I had signed up and added a few friends, but found it a spare and unsatisfying social experience.

Path is the anti-Twitter and the anti-Facebook: You can only share your stream with 50 people. Compared with almost all other social services, it is closed off--and to some (like me)--claustrophobic. Path may be tapping into a need, though. Existing social services are too broad and, by design, encourage people to "friend" or follow others with wanton abandon. That, in turns, leads people to self-censor' if you have 1,000 friends, do you want to share genuinely intimate moments with all of them

Path CEO Dave Morin in the company&39's new downtown San Francisco office.

With Path, since you have a limited number of friends you can add, you have to decide for each person--is this person really among my closest friends Then, OK, I can share a photo from my kid's hospital visit. It is true that you can do this in Facebook, with the "limited profile" feature. But according to Morin, who worked at Facebook and helped create the Facebook Platform, fewer than 5 percent of Facebook users use this feature.

So Path has locked itself into a slow growth curve. It'll never supernova like Facebook or Twitter did. Then there's an accessibility problem. Until very recently, only iPhone owners could use Path. If you wanted to share pictures with your mother but she didn't have an iPhone, you were both out of luck. That recently changed, as you can now "friend" people with just e-mail addresses' photos can be viewed in the e-mail messages people get.

Path also felt small due to its very limited interaction features. You could post photos and flag places and people, but you could neither add commentary (other than flagging a photo as being a "thing") nor get followers' comments on your posts. Today, finally, that's changing, as Path is adding a real-time commenting feature, Path Chat, to the iPhone version of the site. E-mail and Web commenting will get layered in later.

Commenting makes Path an actual dialog. Prior to this feature, it felt like a broadcast service (Twitter at its worst) but with a really weak transmitting antenna due to the follower count limitation. Now that you can actually put captions on photos and have a dialogue with your friends, it's like a more intimate and better-looking Facebook.

Path gives iPhone users a very attractive tool for sharing photos with (only) their closest friends.

An Android version of Path is also in development. So is some form of Facebook integration.

The real puzzler for me is Path's business model. It's a free service, but it has a tight governor on user growth. It'll get location-based ads at some point, says Morin, but without an aggressive user growth model that won't generate much money. The real revenue stream, Morin says, hinges on the big existing market for "expression goods"--custom personal trinkets spun off from users' content. Initially I thought this meant that Path users would be able to throw personalized, virtual sheep at each other, but perhaps there's a bit more to it. Photo sharing sites make money when users buy prints, mugs, shirts, and calendars, for example. And if Path becomes the site where you share the kinds of pictures that find their way onto mugs, there might be a few bucks in that.

Morin points out that services like Evernote and Dropbox, which are free, not necessarily social, and have rabid fans, "convert" their users to paid accounts at a very high rate, 5 percent to 10 percent. I admit I still don't see people signing up to pay for a limited social network, although if (big if) close family and friend circles start to rely on this service, some users could be convinced to upgrade to a paid account if they got additional features, perhaps optional Instagram-like effects for their photos. Or, maybe, a higher friend-count maximum, even if that would be antithetical to Path as it is today.

I get Path now, although personally it's still not working for me as a must-have sharing service. Nor does it read for me as a killer business. The team is top-notch, though. Investors Kleiner-Perkins and Index Ventures have put $8.5 million into this operation, clearly betting on the team's ability to carve a bit of the social network space out of Facebook's hide. I wouldn't bet against this team, especially now that it's well-funded enough that it can take big risks and change directions a few times. I would only bet that if Path succeeds, the product won't look much like the Path we know today.

Related: Path, Instagram, and what the 'Facebook mafia' sees.