It is rare, but I've never heard anyone saying it is *good*. Mind you I have a thing for SF2 and there are plenty that hate it.
Wouldn't pay more than 1200 for one. Keep in mind rare is not necessarily desirable. For years Godzilla was a sub 2k game. It started creeping up because people figure out its great for tournaments due to even scoring. LIS still gets no love because of the shallow code and it has half the production of Barb Wire.