Dr. Drang on Fantastical:
This is not just eye candy. The animations are providing instant feedback on how Fantastical is parsing your words and, more important, they’re teaching you Fantastical’s syntax. This is tremendously useful because, despite the wonderful flexibility of NLP, there’s always a syntax and you need to learn it if you’re going to use the product. This lack of instant, incremental feedback is what makes Siri impenetrable to some people; you have to give Siri an entire command and wait to see how she interprets it.
I’ve used Fantastical on my MacBook since it first came out, and it’s become my main calendar app on my iPhone since the iPhone app was released.