It's only useful until websites start filtering out the receivee domain - that's been happening with a few disposable email addresses.
And the highlight on " We even automatically click on common activation links for you" was a bit confusing. I was expecting a link to a page about the pointlessness of Challenge Response.
And what I really dearly want is an anonymous way to send an email - I don't mind having to sign up; I don't mind having to pay; but I really want a method where sending an email to $Person means they have to work very hard to get my real identity. (This is for good, not bad, reasons. But I can see the potential for abuse.)