I have the great pleasure of wielding this weapon.
The raw unadjusted DPS of this item due to JUST the proc alone is 37 DPS. This is with dex at 305 on Al'kabor. This does not factor in crits and resists.
PC side, the DPS is 59 (the procmod was changed from 0, to +1, then to +58). This is likely the best weapon DPS from a proc alone up to the PoP expansion.
I assume that for Enchanters, Magicians and Necromancers that no cold focuses affect it. HOWEVER, for wizards, cold focuses DO affect it, further upping its DPS. (Until a non-wizard on Al'kabor has it, I have no way of personally verifying this, I'll update it when someone does.)
I believe that for classes that can cast a particular spell, that if they have an item that procs the same effect, that some focuses might affect it. In this weapon's case, a cold focus does affect it if you're a wizard. A bard's nuke song might also affect it, but I've yet parse a fight with a bard in group. I'll do so at some point and state if it does or not.
Overall, this weapon yeilds better dps than medding while fighting a raid mob, and is an excellent companion when rune tanking (it sometimes goes off during the 2.25 seconds when you can't do anything and are just waiting for the spell icon to light up).
Mostly though... can you ever get tired of seeing Ice Comet go off ;-)