Use the search function. There's a lot that's already been written about Alliant/CSPP on these forums. I feel, along with many others, that Alliant will let almost anyone in since they are a for-profit business, and has flooded the California market. There was a research study published a while back saying that the demand for psychologists in the state is full, if not overcrowded in metropolitan areas, and will only worsen in the future.
The big issue, on an individual basis, is that you graduate with 100-200k in loans, which will be burdensome for many years when you're making a low psychologists' income.
Furthermore, Alliant's match rates are poor, and it is difficult to get an APA-approved internship in CA coming from Alliant/CSPP, compared to a legitamate university-based Ph.D. program. There are people who have graduated from such schools on these very forums, and gone back to med school because their financial advisor pointed out that it would be easier to pay back the huge loans that way than continue as a psychologist.
It's just not worth it unless you're independently wealthy, in my opinion. And even so, I don't agree with supporting these type of schools, because they care more about their $$$ than being responsible to their students by only admitting enough people as there are internship spots/jobs.