I've been a loyal Google user for many years simply because their free search feature provides me the answers to my questions very quickly, and accurately. The folks at Google have a sense of humor and history, so they often show a different logo on their site to commemorate something important or fanciful. Recently they decided to change their iconic logo. Here's the familiar, old logo with a serif font style:
I like the serif font choice because it adds a touch of class to the logo, and is easy to read.
Now for the new Google logo with san-serif font:
With this new font the logo looks more child-like and simple, not at all sophisticated. There is a general trend now on the web to make graphics and logos super-sized, which to me looks a bit childish and doesn't appeal to my sense of design. Of course, this is just my impression about the graphical feel for the new Google logo, others may just love it.
So it goes with your web site, the decisions that you make for your logo, font colors and sizes, type face, and combinations of graphics with text will all combine to create a feeling for your visitors. Do you want to come across as business-like, or playful? It all depends on your market place. A CPA or banker will want to appear more formal, while an author of children's books may want to be rather playful in appearance and content.