On one side I always used Google service under presumption that Google is already collecting and analyzing all of its data as a complete profile.
On the other hand I really dislike the way Google is heading.
In the olden days when Google was dumber having high Google Fu allowed you to get required information faster and with greater accuracy. When Google was dumber you could use its flaws to get where you wanted.
Today it just picks whatever it believes is what you are searching for and wont budge. This is especially annoying when you are just starting out on a search of a topic you know nothing about and need a random factor to get going.