Marissa Mayer, the 20th employee ever hired by Google who rose to become one of its leading executives, has been recruited to lead rival web platform Yahoo. Mayer’s appointment comes at a time when Yahoo’s standing among the giants of the internet is weakened, following intense competition with Facebook in which the social network has conquered valuable swathes of the online advertising market.

Mayer will be Yahoo’s third CEO in a year.

At Google, Mayer’s leadership skills have expressed themselves in the form of trailblazing products, such as Gmail and Google Maps. She was also responsible for developing the overall clean aesthetic that runs throughout the various faces of Google’s online presence. Her appointment suggests that Yahoo is keen to innovate and re-attract users with equally eye-catching tools and services.

In a statement, Mayer said: “This is a very competitive and tough space. I don’t think that success is by any means guaranteed.” However, she did signal a determination to impress her vision upon her new company. “My focus is always end-users, great technology and terrific talent.”

Here are some of the reactions that have come in from industry experts and market analysts:

Eric Schmidt – Google executive chairman:
“I promoted her through the ranks and she is now running this [Google Maps] business, which is a lot of money. It’s a nice big step for her. It’s a loss for Google.”

Paul Buchheit – Gmail engineer and partner at startup house Y-Combinator:
“She’s going to bring in a different perspective. It’s pretty clear Yahoo needs a new direction and really a new vision.”

Scott Kessler – Standard & Poor Capital IQ equity analyst:
“A lot of people did not believe that Yahoo could get someone of the calibre of a Marissa Mayer to become the CEO at this stage.”

Marc Andreessen – technology venture capitalist:
“It’s a very big commitment on the board’s part to pursue a product-centric strategy, [and] it’s a big job that Marissa is stepping into.”

Image of Marissa Mayer courtesy of Wikipedia