To anyone complaining this is not open-source, the people that make this software disclose as much in the system requirements on the same page where you download it. If you are having problems downloading it, that is probably because you tried to use bogus information to register an account (I tried this, and failed too), they are very strict about it. Once I paid attention to what it said on the registration page about not using bogus registration information I was able to get a copy after updating my user profile.

The example templates are rudimentary, but not proprietary, it was easy to incorporate a $20 bootstrap template I found, and I am very happy with the results.

I also needed to send contact info from this software to a bulk email service, and the API made that fairly easy, my questions about how to do it were answered by the developer promptly. I am discovering that I can do and control just about anything, including the kitchen sink.

I'm a web developer and very frustrated with this software. The name suggests that it is open source but it is NOT and it's almost impossible to download the free version for testing purposes. The overall design is from to the previous century.

I am using Open Realty for several Real Estate (Realty) sites and many other scripts for different function sites.
I have found Open Realty to be flexible and easy to use whilst being well featured.

Overall though, I judge suppliers of Scripts when you have a few bugs to sort out. That is when you know you have selected the right product.
Open Realty has been the most prompt and helpful of all of the scripts I have used, both paid and free.

If you are looking to build a Real Estate site, I give Transparent Technologies Open Realty a big Thumbs up!

Pros:
Low cost for pro version, and upgrading from free version is completely painless. Software is fully featured, and very extensible. Real estate information can be customized and manipulated to an extent I will probably never take advantage of. Support staff is very knowledgable about real estate and MLS rules and procedures as well as web hosting. Over 8000 listings on my customer's site and going strong.

Cons:
A bit of a learning curve. Not for the impatient.
Plugin system and developer's materials could use more examples.

Advice:
Do not just assume your hosting is compatible with this software, make sure before installing it, save yourself a lot of headaches. If you are going to import listings from IDX, make sure you get all the documentation available from the MLS before you start. If you are setting this up for someone else and have not used it before, give yourself plenty of time beforehand to experiment and ask questions.

This is a terribly inflexible piece of software that struggles to perform under even moderate server loads. When you try to login to the administration area of the site, it always makes you log in twice. It used to be open source, but the developers made the mistake of closing the source code several years ago. If you're a developer, steer clear of this abomination.