Summary: I've used the DIR-655 since mid-late 2007 when I bought it to replace a malfunctioning Linksys router at my former company, supporting 100+ users.
Over the months I had the DIR-655 supporting secure wireless connections for employee workstations, I rarely needed to give it any attention - it just worked.
I recently bought the Linksys WRT600N hoping to use it as a Media Server with it's USB port designed to be connected to storage devices. This failed miserably. I returned the WRT600N and got the DIR-655 in exchange; the D-Link DIR-655 has been working perfectly.
My only real disappointment is the lack of USB port for use as a media server; for that, it seems I'll have to invest in a proper network storage box.