I know quite a few individuals in the program. Great program, wonderful reputation--tons of opportunity for collaboration, research, clinical experience, etc. It's an awesome place for networking. The neuropsych track is particularly strong (as are the others). While entering cohorts are generally larger than other schools, this is not because each faculty mentor takes more than one student--rather there are many faculty members between the two schools. Each cohort is generally very close to their own cohort and know individuals in other cohorts based on clinic supervision groups, similar labs, or similar tracks. The training is great as well. The quarter system at UCSD and the semester system at SDSU make things a bit odd in terms of time off, but I don't know anyone that has complained about this. Depending on who your adviser will be though, the level of flexibility between lab/clinic/classes will vary. I know many of the faculty so feel free to PM me with specific questions.
San diego as a city is WONDERFUL. Tons to do, lots of places to go--if you live closer to UCSD you'll be very close to the beach and hiking, close to SDSU you'll be closer to just hiking. The sun is out 95% of the year, and the weather is HEAVENLY. While the students are very serious about their work/classes, they do also take time to have fun. The cohort I know most tends to go out a lot together and people do make time to relax and try new things. There are awesome restaurants out here as well. Cost of living on the other hand, is pretty high. (More expensive towards UCSD, but still relatively pricey near SDSU). Will you be living with a partner, roommate, or alone? What is the other school you're considering if you don't mind me asking?
Again, feel free to contact me with specific questions and congratulations! This is many people's dream program and it's amazing to have been accepted.