I depended so much on this forum when I was applying for schools so I thought I'd put myself out there as a resource for anyone who is thinking of applying to GSPP. I'm a current student, focusing on international environmental policy and sustainable development.
To give you a short list of why I chose GSPP over other options: Berkeley is hands down the best place to be for those interested in energy/environment/sustainability, there are amazing research opportunities in every field, the program is extremely flexible but also quantitatively rigorous, and $$. I know that when I was trying to choose a school, debt was a huge factor. In my opinion, GSPP does not do a good enough job advertising how generous they are with funding. Even if you do not receive a fellowship, there are a ton of research and TA positions available that a) provide fee remission and pay a very very generous living stipend. This is why I will graduate with 20k in debt versus 70-100k I would be taking on had I gone with SAIS or SIPA.
If you're thinking of applying and have any questions about the program, Berkeley, student life, etc...ask away!