Things I did like: I was on a small team, my team and manager were great people, and I got along with everyone. The work environment was very comfortable, great food, they got me a super comfortable chair when I complained about back pain, etc. The pay was great too, enough to save 40-80K per year depending on spending habits (and still live comfortably!)
One thing I didn't like was living in the silicon valley suburbs. It felt like a small town with nothing going on for me. It was really car-centric, my apartment came with a covered parking spot because they just assumed that of course you have a car. If I had to do it again I'd get a job in SF and live in SF. I don't want long commutes and I don't want to live in suburbs. Since you're from a small town, YMMV. The SV suburbs might feel like a big upgrade to you, and having to drive everywhere might be something you're already used to.
Another thing was that the work was dry. This might be very different for you based on what employer and job you pick. My team was doing mostly maintenance and incremental upgrades on a product many years old. I found that dreadfully boring. I need something creative. This is something I didn't know then. My current job doesn't pay nearly as much but the work offers a lot more novelty and creative freedom. If I had to do it again, I'd make sure to join a team that's working on a project that has me genuinely excited, preferably a team that's building something rather than doing maintenance.
It was also really hard for me to be uprooted from my hometown where I'd always lived and away from my friends. What made it even harder was that I fell into a depression right before moving to California. My mother was suddenly hospitalized, right as I was going through other stressful things and preparing for an international move. The extra stress was too much. Then I landed in California, and I had to start my first job, and I didn't have any friends there to support me. It's hard to boostrap a network of friends starting from nobody, and it's even harder when you're depressed... You have no energy to go out and you're coming from a place where you need people to help and support you, rather than a place of "I'm a fun person to spend time with".
Lastly, while I lived in California, after being on antidepressants for a bit and feeling more hopeful again, I tried dating, and I hated my experience. It feels, to me, like SV has an overabundance of men, because of the constant inflow of tech workers. If you're a single guy, you're moving to a place where there are too many men. In any other city, being a successful tech worker is something that will earn you points, but in SV, every woman knows they could date a Google engineer if they wanted to, at least that's how it seemed to me. Lots of ghosting and being treated in ways that I found disrespectful. To make matters more complicated, lots of people in and around SF are polyamorous, which is not something I want to get involved with.