Vantaggi
No matter what it's become, eBay is still the place the pioneered ecommerce. There's something to be said for that - and to the extent that you can squeeze some learning out of the heritage of the place it's a good place to be.
Svantaggi
Senior Management (and I mean the TOP senior management) has no clue what they're doing. They don't actually use the site, and spend all of their time looking at data about OTHER PEOPLE who use the site. They then try to draw conclusions based on their review of that data, but since they have no visceral experience with the site their conclusions are often incorrect in subtle ways that doom whatever initiative they're proposing. They then try to remedy this situation by looking at even more data, and the cycle continues. John Donahoe has never RUN a real company (consulting doesn't count), and it all starts with him.