I haven't voted (yet) as I don't worm regularly so haven't used anything since July 1st. Not sure whether the date is important, which is why I've not voted so far. When I do worm I use Drontal and I probably worm about 3 times a year.
Would say it is effective as he doesn't have any worms that I'm aware of. No reaction, ever. I find it very easy to worm him. Wormers are never given around vaccinations since I, a) rarely vaccinate and b) don't like putting too many chemicals in let alone an overdose to his system.