Pros
eBay is an exciting environment with a lot of cutting edge issues. There are a lot of really smart people who work there. It's fun to work for a company that is in the news every day. They have a lot of great subsidiaries.
Cons
It's a sweatshop and a very political environment. If you don't play the game, you won't advance. It is also a very male dominated company - women who have children are almost always knocked off the track. There was a several year period where approx. 40 people made VP - only one of which was a woman. The morale is very low, with most employees under water on their stock. There have been a lot of management shakeups and people are waiting to see if they will deliver. What once was one of the most cutting edge websites got lapped by a lot of other companies - now they are trying to play catch up. It depends on the department, but there are some very bad managers at senior levels who are tolerated/ignored by the rest. The company is also very stingy - 2-3% raises, no childcare, no subsidized meals, no holiday parties for many departments (with $4 billion in cash in the bank).