Pros
Great pay, work whenever convenient for you. The free food is simply amazing. Lots of perks like massages, micro kitchens, tech talks. The tech stops and hardware depots are great assets, you can go pick up headphones or a new keyboard and mouse for office use. The work place is very open, interaction with other employees is very easy. It is filled with very intelligent and fun people. The company is very open, you can ask questions directly to the CEO or Founders during TGIF question and answer sessions. Interns don't get nearly as much perks and benefits as full time employees, but that's expected. Google probably has one of the highest pays for interns. It is definitely one of the best places to work at.
Cons
Promotions don't seem to happen too often due to the fact that there is very short chain of command and little bureaucracy.