My thoughts:
Status->Statistics:
menus seems somehow...misaligned (IE, labels aren't clearly related to any of the numbers floating around below them)
Tools->System Check:
It'd seem more logical to name that menu "ping test" since that what it calls itself when you select it. But that's probably just me...
Advanced->Port Forwarding (and other menus like it)
Seems to enjoy asking me if I want to save settings, even though I haven't even selected any particular box/changed anything at all. (the other menus with lots of input boxes/menus do the same...sometimes)
Advanced->Guest Zone
Menu isn't grayed out when wireless is completely disabled (it should be, because if wireless radio is off, how can I setup a guest zone?!) Though I'm sure that's not a priority, since most people probably bought the router FOR the wireless...not because it worked out to be the cheapest with a gigabit switch. :S
As far as actual functionality goes, DNS relay seems to work but the router *STILL* seems to confuse mdns broadcast clients in some way I haven't quite been able to track down. But ~mostly~ usable now, only when a client "fails" to get detected by the other mdns machines does it become problematic (in that it itself will be unable to resolve any *.local names for a few hours, and others can't see it, though sometimes other machines can resolve the troubled one's name, but not the other way around.
Its a little weird, and really hard to trigger the situation intentionally. BUT I can say that if I put my old DI-604 back in as my gateway, it works without a problem, so, either the DIR-655 is "right" and breaks stuff, or the DI-604 is broken and lets everything work when it shouldn't.
On a note related to the DI-604, its DHCP server (as screwed up as it was) would give the same address to my macs weather they were on wireless (I use a WRT54G for wireless not the 655 due to placement) or wired, this allowed them (somehow) to switch media types without interrupting any open connections, it was REALLY nice. But I'm sure that it was actually the DI-604's brokenness (or something in the verizon firmware).