I have used make low cost UTM type products, from Linksys, NetGear, and more. However, this device has to be the biggest piece of trash I have ever wasted money to purchase and let me explain why...
I have a small business office, with two wired servers, one wired VoIP phone, and four wireless clients. At first, every time we used the VoIP phone wireless service disconnects. D-Link support explains that their QoS service can not handle load, if you can consider a single 64Kbps VoIP load, but we disable QoS and at least the wireless doesn't disable.
However, again we seem to be hitting a point where this device can not handle our traffic, as every time we have all four wireless connections running our internet is down to to hour glasses. Also, every system was checked and even packet sniffed the network - no one is running a torrent client or streaming.
I find this very sad, considering that we have a larger office using an open-source linux firewall/router on a P3 that handles more then this device. IMHO this device should have a warning label that its QoS doesn't really work and it can not handle small networking. I wish I could return this device, but I think I am just going to being it outside and drive a stake through it so no one else has to deal with its very poor performance.