Yes, that's actually the direction I was aiming for, a little bit like the Slashdot system.
I just think it's very hard to choose meaningful adjectives/dimensions (the slashdot set also quickly feels limiting). That's why I'd start with the most basic sentiment(s) first (positive|negative, agree|disagree, ...), see how that goes, and possibly extend from there.
Not with commenting but with classifying the comments.
As maxerickson said we'd have additional votes for adjectives like e.g. "mean", "interesting", "funny" and others, but the hard part would be to choose a meaningful set.
I think almost any set would probably feel arbitrary and limiting quickly, so I'd rather stick with very few, very basic ones and see how that goes.
I think the bigger problem is what to do with the extra information.
In that light, something like "too far off topic" is probably more useful (I think the too far is good there, as a reminder that things probably ought to range a bit).
