Of all the location-based apps that are making a splash here at SXSW 2012, Sonar is the one that's been maneuvering more or less under the radar. However, in order to understand the ambient location space well, it's also important to take a look at this app. How does it fare compared to other bigwigs like Highlight, Banjo and Glancee?

First, it's worth recalling the new features the startup has released at SXSW. One important update that Sonar got right before the show started was the addition of an Android version of the app—a much-requested feature, according to founder Brett Martin.

Another change the app underwent was going the Highlight/Glancee route and shifting its emphasis to relevant people within range of your network, instead of focusing on check-ins to particular venues. Previously, the app showed results as a list of places first, and when you drilled into a location, you could see recommended people. Now, you immediately get a people list upfront, sorted by their degree of closeness to you (friends first, then friends of friends, etc.).

As Martin once told TechCrunch, "The most obvious part of it is that Sonar before was very venue-focused…but now we’re doing this thing called ‘people nearby.’”

Using the App

Sonar was easy enough to figure out. First, you connect the app to your different social networks. Twitter, Facebook, LinkedIn and Foursquare were all available. The app cross-references these networks, detecting people in close proximity to your current position, and showing you a list of people ordered by most number of connections, be they mutual Facebook friends, Twitter following, or LinkedIn contacts.

The list of people appears within two tabs found along the top of the app: People and Places. As mentioned, People simply lists nearby folks with strong ties to you. Tap on a person's name, and you'll see their location as a dot on the map. A slider for different social networks across the bottom of the page also let you jump into quick details in their Facebook or Twitter profiles. When you're ready to connect, you can tap on the Twitter icon on the top right corner to send a quick message to a potential new contact.

The Places tab is interesting, too. Here you'll see a list of places that are "hot," ranked according to the number of people that have checked in. Of course at SXSW, the Austin Convention Center was up top, letting me know that 644 people had been there.

When I tapped on the venue, a big button invited me to "Check In here," and below that, showed me a list of people who were currently at the venue, ordered by the same Facebook, Twitter or LinkedIn commonalities.

When I clicked on a person's name, I could see our Foursquare and Facebook mutual connections, check out the person's LinkedIn profile, and see the accounts we mutually followed (or the accounts that mutually followed us) on Twitter. A big button on this page solicited me to "Say hi to @username" via a message on Twitter.

Comparison with Other Location-Based Apps

Comparing Sonar to the other location-based apps we've seen at Southby, we'd say it hews most closely to Banjo. Both apps piggyback on your connections within existing social networks, so you don't have to worry about convincing your other friends to get the app—it has some utility even if you don't necessarily have your whole network of contacts on Sonar. How big or small the user base is also doesn't matter, since you're seeing connections outside of Sonar itself.

However, Sonar suffers from the same criticisms as Banjo as well. Users could get turned off by people who aren't within their network messaging them out of the blue. Unlike joining Highlight and Glancee — where becoming a member essentially signals, "Yes, it's okay to come up to me!" — Sonar lets you peek into already-established networks who may not be as open to meeting new folks as you.

Bottom Line

True to its name, the point of Sonar seems to be a low-key way to find out about the people around you. At a tech-savvy hotbed like Austin during SXSW where everyone has very similar interests, it's an unquestionably intriguing app. But for meeting new people in a regular setting, the app could turn up less than ideal results.