It would be nice if you at least listed what the exercises are before asking for money.
I agree to a degree. Listing a bit more about Vim itself for someone that might be coming from a development background but does not specifically know about Vim and it's benefits could be good, and maybe what TYPE of exercises will be involved (What will I be be able to do at the end) - but keeping the exercises a little secretive is great to keep interest :)
edit: Note, I realize this isn't OP that I'm replying to. Not sure if what I wrote makes that clear.