I think Google Now definitely has better voice recognition, though today I was driving to LAX and tried to say "drive to 6075 Avion Drive" and it couldn't get it after four tries.
The cards are cool, but not perfect. I'm in Los Angeles, and because three weeks ago I searched/navigated to 6075 Sunset Blvd, it randomly throws up cards with that address when it sees I'm leaving Long Beach and entering south LA. Get a little bit more timely and accurate guys...
Once I was in Whole Foods, and it threw up a card that said "hey your in Whole Foods, want to scan items to compare" and the link to the scanner never did work. It definitely feels more powerful than Siri, but Siri is also very useful if you actually try to learn its potential and use it.
I'll never forget the time I was driving through Palm Desert to a Dodger game and realized my tire was about blowout. I pulled off the freeway, in a panic said to Siri "I have a flat tire" and it smoothly brought up the phone number for a place less than a mile away! That's what "personal assistant" really means.