Google

1. Very smart and rational co-workers and managers. Most of them, even the superstars, are down-to-earth and approachable.
2. Good salary and some benefits (e.g., food, drinks, outings, events), even for interns.
3. The general atmosphere is very vibrant, and morale is very upbeat. Both of these contribute to productivity for sure.
4. The ability to make an impact is incredible. There is already a powerful platform with wide reach, so your work is sure to get a "first look." Sustained interest depends upon the usefulness of the contribution, though.
5. Especially for interns, it is a great feeling to have your opinions heard and respected, even on critical long-term projects.
6. Diverse engineering crowd, unlike other tech companies like Cisco and Microsoft, which are Asian/Indian heavy. This is good or bad depending on your preference.

1. Because the peer group is so good, expectations run high. As a result, many people have to put in long hours.

2. Many engineers do not seem to engage in 20% projects. They can do these only if they find time from their main projects, which, due to point 1 above, is difficult without seriously affecting work/life balance.

3. I hear that career growth within the company is challenging. If you are someone who runs after job titles, this is not the place for you. You might end up having the same/similar job titles for many years.

Not in a position to give advice, but I think individual career growth is something that needs to be focused on.