Received mine yesterday. Stock BIOS is a bit choppy, but stable and feature rich. (Actually the only weirdness I've noticed so far is with non-standard settings it seems to jump around a bit while navigating the menus, so you have to go back because it skipped over one as you move down the list.)
I really like the fact you can save BIOS settings profiles with descriptions right inside the CMOS and load them on the fly in case of a crash due to incompatible settings, plus it includes Memtest86 right onboard! It also comes with an LCD readout for error display, plus has a power and reset switch onboard for out-of-case testing. There are also more overclocking settings for this board than many will likely know what to do with. I returned my ASUS A8R32-MVP Deluxe as it failed to allow adding voltage to the CPU core over the stock 1.4v. This board however lets you go up to 1.55v directly, then incrementally beyond that by percents past 1.7v. 1.55v was required for stability at 2.75, so I was unable to achieve this optimal configuration with the ASUS "overclocking" solution.
In terms of performance it seems rock solid. I was able to overclock straight up to 2.75ghz on my Athlon 64 3700+ at 250fsb x11 without any problems; six hours so far running Prime95 without a hitch.
The only thing I don't really care for is the integrated ALC882 RealTek audio, though you can of course disable it in the BIOS and install a third-party card, and the Karajan audio chip itself actually unplugs from the board.
With a single Radeon X1900XTX and 1gig of Corsair TWINX1024-3200PT memory I score 11000+ in 3DMark05. Sandra has my benchmark at this clock almost exactly parallel to the FX-55.