Yes, I use it. I use Google Maps for some things, and Livesearch for other things. I think Google's maps and traffic are easier to read. Livesearch is easier to use to look up places, like restaurants.
I've been using Live Search since it came out and it works great.
If I am looking up a business or restaurant, I use LiveSearch. A simple map query, I use Google Maps.
I also use Blackberry maps because of the integration with the address book (I can get a map to a contact's location).