Pros
Metrics are a huge thing at eBay, except that the meaning of the metrics are completely lost. All that matters is meeting the number. How you meet it is irrelevant. Case in point. There is a metric that no fewer than 50 API bugs be open at 4:00 every Friday. In order to meet this number several strategies are employed: No one is permitted to file bugs on Friday. In extreme cases, bugs are closed even though the reported problem has not been fixed. Both of these are considered appropriate actions because all that matters is meeting the number.
Cons
eBay is so obsessed with measuring one's contribution to the company, that the measurement itself becomes the most common task. One's job becomes an exercise in making powerpoint decks to show that you are making a real difference. My job had nothing to do with eBay. My job was about attending certain meetings through which I could collect raw data that I could then later "spin" into making me (and thus my boss) look like a winner. I was taught how to do it. A successful employee discovers which meetings will give you the BS data you need. If you end a quarter showing that you handled 10% more projects than before, it must mean you are a genius, and you are doing great. Link that increase to a newly launched tool and you'll be a God. Custom built efficiency tools are the key to making unhappy workers more able to "grow" efficiency. Just don't ask for any "train seats" for those tools (God forbid).