Don’t you think you should be up front and say you are the developer of GTDagenda?
It’s totally ok to plug your own product. It’s totally NOT ok to come on a blog where someone has written a detailed review of a competing product and then say, “I would recommend checking out” your own product.
I have a subscription to GTDagenda and am now actively considering cancelling it because of that bit of low-life behavior. It’s uncalled for and you owe Mr. Travis an apology.
Disclaimer: I am a subscriber to GTDagenda, and this is my own opinion.