Out of all the Psi ICE, Snowflake is possibly the best of the lot. It is cheap to rez, which is good because spending money on the Psi game is an additional cost, and it simply ends the run. A good combination that may be often overlooked.
The drawback is of course that it is Psi. The cost to keep the runner out can add up very quickly, and it is not a guarantee that it will do so even if there are no breakers on the table for it. The cost is reduced out of Nisei Division, but that ID hasn’t seen enough reason to be run yet.