QUOTE(HoNeYdEwBoY @ Feb 13 2012, 06:40 PM)
pro and cons are here
Advantages of Using DD-WRT firmware
The router gets increased stability
Less lockups/crashes
Less connection drops (I'm looking at you, generic VPN protocol!)
Support for a larger amount of concurrent connections
The ability to increase your wifi signal strength (stock firmware has really weak wifi transmit power)
Disadvantages of Using DD-WRT firmware
Unifi home users (VIP5/10/20) lose IPTV access
You lose TM support for your Unifi service (it was pretty much non-existent in the first place!)
You probably void the warranty on the router
You might brick the router if you don't know what you're doing
more explanation see here
http://unifi.athena.my/ddwrt_guide.php