I'm having a very similar issue. I just received my Mini and WLAN is pretty much useless. I've mucked with the antenna wires, performed an update (it's Ubuntu based) and poked around at log files and such to try and get more info. It has to be some kind of bad packet problem. NetworkManager (Ubuntu's network config tool) claims the connection is 54MB, but if I ping my desktop machine, I get anywhere from 20% to 60% packet loss. Ping times seem reasonable with ~3ms on average.
Wireless access is the reason for this thing to exist. If there is one thing that needs to work our of the box, it's WLAN. Sheesh.