A Webmaster Blog
Google’s stuff lacks the usability of Yahoo’s services, the “intimate connection in usability” Yahoo has with its users.
Comparing usage of Yahoo’s email and instant messaging versus those from Google. Yahoo has a big edge in email users, with 249 million. Gmail has picked up 60 million users.
On the Instant desktop messenger side, Yahoo’s 77.9 million users are well ahead of Google Talk’s 3.4 million. The typical Internet user needs a good usability experience to go along with the functionality.
Also check the previous post on difference between yahoo and Google.
You can also check the other search engines like AskX.com which concentrates well on usability giving a lot of options.