I've seen Revolution work perfectly on some dogs and I've seen it work horribly. My experience, for what it's worth:
1 - Siberian Husky A - lived near a wooded area. Got covered with ticks even while on Revolution. Switched to a different topical after vet removed all ticks. Worked fine.
2 - Siberian Husky B - not in a wooded area, but it's the south, tons of mosquitoes. Got heartworms 2x while on Revolution. I quit using Revolution after that.
3 - Bichon Frise - owned by a friend of mine. Gave him Revolution for several years, never any problems. One dose of Revolution eventually caused him to become lethargic, then soon seizures, following by vomitting, paralysis, then death. This was over a 2-3 day period after administering the Revolution. They did an autopsy and ruled it was caused by the Revolution.
I don't use Revolution any more after these three personal experiences.