Pros
Tons of smart people, great benefits, nice physical environment. Customers really do love the product and let you know what you've done right and wrong. There are good chances to advance, if you like limiting yourself to company niches, and can hack no life outside of work.
Cons
eBay is the flagship brand, but the other companies (PayPal, especially) are the tugs that pull the big ass eBay tanker through the narrows to boost profitability. Everyone expects you to drink the eBay Kool-Aid, and look askance at you if you question the big fat rah-rah-rah. On the development side, there are WAY too many managers. The product development process if horribly inefficient. Schedules across groups and projects are continually out of sync. The audit trail is ridiculous - for every bit of code you touch or test, you have to fill out at least 3 checklists. There are more employees dedicated to tracking status than testing for many projects. This company works you to the bone, is cheap, pushes deadlines over quality and tries to do too much with too little. But the benefits are good.