I have spent some time comparing it to my MkIII (Black and Orange) Oddy, and so far it's a pretty good emulation, but...
A couple of things niggle me - the portamento isn't right at all, the ASB is too "linear" ie. straight from one note to the next - my Oddy's portamento starts quickly and slows down as it reaches the new note (logarithmic?)... I wish I could describe it better than that, but I can't

The other thing is the ADSR sustain slider, on the genuine Oddy, if you play a sound that is set up to just use decay *then* raise the sustain slider, the sound fades back in... not working with the ASB.
The "ARP" filter is also slightly different - not sure what filter version the ASB is based on, but my Oddy has the last version (with the 12k bandwidth problem - I never bothered to get it fixed... just a couple of resistors to be replaced I think).
Apart from that, It's a superb bit of kit.