I love it. I wish I could report that my spam has dropped due to Sneakemail, but unfortunately I can't say that. My spam has only increased lately. I can say this, however. While I haven't had a real spam problem, I use Sneakemail to prevent one from occurring.
Prevention is better than cure.
And one of the preventive measures, in my opinion, is something other people may see as a negative. That Sneakemail signature at the bottom of each sent email needn't be viewed as just advertising which pollutes your letters. I see it as a subtle warning to the recipients that since I'm using this service, they should think twice before spamming me. So far I haven't had a single piece of spam from such recipients.