Funny thing is I think my Abit BF6 (440BX) mobo that I still have after 9 years now is one of the most troublesome boards I've ever owned. It isn't particularly stable, but most notably it has big problems with PCI IRQ sharing. It will simply not boot with some cards in certain slots. I'm not sure if ASUS P2B was better, but Abit's 440BX boards were not perfect by any stretch (how bout that HPT ATA66 chip! yikes). I've worked with BE6-II, ZM6, BH6, BF6, BX133, KT7A, NF7-S 2.0, and KW7.
Softmenu was definitely what got them the positive press. This feature was neat back then, but it certainly wasn't a sign of superior quality or workmanship. I think their tweaking options are about all they had going for them that was ahead of the rest and that advantage died really quickly.
They also went through all of the capacitor espionage + bursting problems with most other manufacturers, meaning most of their boards from 1999-2003 or so are probably unstable or dead. My BF6 had bad caps but I recapped it. Also had a dead BX133 with burst caps everywhere. What sticks in my mind about those cap problems is that the OEM boards (Dell, Gateway, etc) from Intel are fine, unlike most of the cheaply built "enthusiast" boards (i.e. Abit, ASUS, Shuttle, Epox, Iwill, yada yada).
I think their "peak" was probably the NF7-S 2.0. The board still fetches good money second hand. Contrary to the infinite enthusiast love for it, it has its problems, mostly caused by the NVIDIA drivers though (audio & IDE come to mind.) And it had one of those cheap northbridge heatsink+fans that always die. I purposely went for a Shuttle AN35N instead because it had a passive cooler and I didn't care for expensive onboard audio that needed an optical output connection to sound any good. Good call on that too because NVIDIA didn't put much work into the drivers.
I guess what I mean to say here is that they were usually ok boards but I never saw them as exceptional. The press talked them up like they were the best thing ever, but experience tells me otherwise.
