I haven't tried the 12 but did go through a bottle of the 21 in short order. To me, the defining characteristic was balance, though it absolutely had maritime traits. I'd love to get more but it's outrageously expensive in Ontario.
It's a much mellower scotch than both the Lagavulin (16) and the Talisker (10). Not sure how it compares to the Talisker 18--haven't sampled that one yet.
I'm in Ontario as well... doesn't appear to be much selection of OP at LCBO either
Do you ever buy scotch from anywhere other than the LCBO?