If you're a Googler, Mazel Tov. If you're not, it's a great place to work for one year. They give you broad latitude to do whatever you want, so you can do nothing, you can find a real job or you can do something truly amazing to put on your resume. Then, you've essentially become an expert in that area and you can use it to find a real job.
If you work there for more than a year, you're just waiting to die. Your professional growth will not exceed beyond your own whim. Your likelihood for advancement will be nothing because nobody every got promoted at Google for building a strong team.
Perfect to gild your resume and practicing the skills you want to develop
Worthless for anything else.