Hi:
I think the benefit of Joomla is exactly what you mentioned, all the great applications that exist for it and ease of installation. On top of that you have the template clubs which produce some pretty amazing templates for Joomla.
You are right that the search by zip code functionality does not exist right now. Keep in mind that jReviews is less than 6 months old. It's still priced well below other programs but that may change over time as it becomes even more stable and feature rich. I know the product you mention is far far more expensive and does not have the posibility of integrating with all the other great extensions out there.
As an example of integration. jReviews automatically integrates with Community Builder, creating links from user names to their profiles and showing user avatars if they exists. There's also a jReviews addon that integrates it with one of the native forum boards for Joomla (Joomlaboard) and you can read more about that in the product descriptions. In the tips and tricks board in the forum here you can read about what you can do with other Joomla plugins and jReviews. In short, the Joomla system works very well.
I cannot talk much about standalone programs because I don't know them. The good thing is that you can try it out. Install Joomla, grab a few of the extensions from the
http://extensions.joomla.org site, get a free trial of jReviews and see how it goes and compare that to having to create everything from scratch with standalone programs
Happy Holidays!
