I would say prices in general are up, not down. You can get some last minute prices that are pretty decent if you're flexible enough to do that (of course, the airfare to get to the cruise in that case can cost more than the cruise does). But things that are booked out in advance have seemed to be higher than in years past. (Alaska in particular seems pretty high to me right now.)

Some of the cruise lines have made adjustments to their Med cruises based on things going on there, and I think some of the stops in Turkey may be getting awfully close to getting dropped from some itineraries (which would be a shame), but for the most part, I don't really think ISIS is having much of an impact on actual bookings for Med cruises.