They clearly don't explain irony, then.
I've downloaded Duolingo... IMHO it's a useful addition to have on your phone to complement Rosetta Stone when away from the laptop to keep the brain ticking over, but it's not the same league as Rosetta Stone in terms of content and doesn't have the same total immersion method of learning (i.e. no english whatsoever), which is what makes Rosetta Stone so good. Thanks for the suggesting though, I'll use both!!
That's the spirit fleece them.X)
You might want to give it a try..
TCB offers 15% fastback as well, it worked for me, so hope it does for you.