I've installed a series of Wireless Networks at the lowest cost possible for business and individuals. Previously, the best systems were business grade routers that were hard to setup but once setup, never needed to be rebooted or touched. This always limited you though in the scope of what you could cover. Expansion was difficult the say the least and complicated guest networking and payment were super challenging to setup.
I was a little skeptical of the Ubiquity's UniFi system with it's low cost and server based control of the access points. It made sense, put everything into the software and let the device just be an AP. Setup was a breeze. I put the software on a Windows 7 Server and connected the AP's to the network. The range was amazing. Setting up a simple guest network that points people at our website took a few clicks. Tracking and monitoring happens from anything with a webbrowser.
I ultimately gave up on the Windows Server because everytime the user logged out, the wireless guest network went down (or just let anyone get on). I found a junker box, threw debian on it and installed the Linux version of the software. The box sits in a closet with Webmin on it and I can monitor the box and the wireless network through my iPad anywhere in the building.
If you're looking for great coverage, expandability and a configurable wireless network, this system is the way to go.