A unique feature for a router in this price range (approx US $300) is it has 2 WAN interfaces which means redundant internet connections. As of firmware version 188.8.131.52, it supports two types of QOS under "System Management" -> "Bandwidth Management", the first is a prioritization based on port and the second, a "flow control" guaranteeing minimum bandwidth.
Our experience has been that it is essential to set the WAN MTU manually to 1492. The default settings do not work well with Asterisk and SIP. We had numerous problems with dropped calls and phones becoming "unreachable" for minutes at a time until this change was made.