Originally posted by NeverSatisfied I've had both and ended up getting rid of the 21 - I just didn't use it enough. 12mm is WAY wider than 21, plus I swear the IQ on the 12-24 is just as good. The DA 12-24 *is* quite physically larger but I don't consider it "heavy" by any means (try a Tamron or Sigma 70-200 for "heavy"!) The zoom is definitely more versatile. Something like a CPL for for it will cost more (77mm) but personally I can use the one CPL between three different lenses I own so it wasn't a waste...
I have the DA 12-24. The IQ is very good! Never used the 21mm pancake, but my guess is that the 12-24's IQ at 21mm is the same or better than the 21mm Limited's.
As far as size goes, it's not a big lens, IMO.