Mayer is widely credited with bringing a clean user experience to many of Google's products, where she most recently was head of local, maps, and location services. But her background does not include media or display ads. Yahoo describes itself as a media company, and display advertising is its revenue "bread and butter," according to Rebecca Lieb, an Altimeter Group analyst.

Allen Weiner, an analyst at Garter, said Mayer was not the "safe choice" for Yahoo because her experience lies in products rather than media, which is Yahoo's main focus.

"But she's a great choice in that all constituents -- the board, the public, advertisers, users -- they're all going to be really happy with what she represents in terms of background, experience and presence," Weiner said.

Mayer's first task, Weiner said, should be to persuade interim CEO Ross Levinsohn, whose background is in media, to stay on to share his media expertise despite being passed over for the top spot.

Mayer will also need to hire "strong teams" to handle Yahoo's display ad business, which is not a significant part of what Google does, Lieb said.