Zillow has released a free iPhone application that will allow users to access property values and other real estate information (such as photos and agent contact) on the go. The app goes even further and allows users to locate open houses via GPS and to pop up price information as a user passes by a property. Homes for sale can be plotted out on a map. Zillow’s iPhone app grabs data both from the company’s Zestimates and Make Me Move sections.

Initial reviews have been mixed. SFGate.com, for example, called the application “buggy, incomplete and occasionally maddeningly slow,” but also admits that it is “easy to use and quickly draws out your inner voyeur.” Zillow can call up details on 3.3 million for-sale listings plus 95 percent of all U.S. homes, not just those on the market.

Zillow isn’t the first to offer such functionality, of course. Trulia did the same last year (an updated version came out in February) and has already had 170,000 downloads.

The Zillow iPhone app is an improvement over simply accessing Zillow via the Web browser. On a Blackberry for example, the map doesn’t appear.

For Realtors, the iPhone app is good news. Users can call or send an e-mail to an agent with one click.

Zillow CEO Spencer Rascoff was enthusiastic about his company’s new product. “To be honest, I think the iPhone app…might be better than our Web site” he told Inman News. For example, iPhone users can pinch to “pan and zoom” images on the iPhone. On the computer, this would require mousing and scrolling.