I know lots of Brits and Canadians in California who have also followed this path.
A lot of talk in here about H1B visas, and that's probably because they're the most plentiful. But, that's not the only type of visa that people should be thinking about.
You can also try to convince your employer to keep applying for an H1 for you while you are working on an L1 - if they agree that's usually a good sign the employer is going to work hard to complete your GC process, and isn't just using the L1 status to handcuff you to the company.
Sky high property prices across the country compared to wages (not just on the coast or in London, everywhere).
Low salaries and high cost of living compared to equally developed countries.
Chronically underfunded public services but ever increasing taxation.
It rains a lot and the weather miserable, this is the biggest one for us personally.