I went off and did my own startup for 2.5 years, and then wound up crawling back to corporate America.
I believed in 'following my passion' when I left, and I definitely wasn't finding that at Google. After all, my last project there was building automated tools to serve legal requests for Google+ - not exactly what you have in mind when you join.
A couple of things I wish I had known when I left:
- Following your passion is bunk. Most people don't understand themselves well enough to know what they're passionate about. There are always going to be parts of jobs that you don't like, even when you're working on your own stuff. I actually found the percentage of dislike to increase when I was doing my own stuff - I had to do sales and marketing for my own company. I never had to worry about that at Google.
- A lot of people try to find some larger meaning for what they're working on. I always wanted to work on 'something really important', and I wasn't finding that at Google. Problem is there just aren't that many 'really important' things. Even if you work on phenomenally successful products like the iphone, you could argue that product did not make the world much better in any meaningful way. What's worse, 80% of software developers spend their careers making glorified CRUD apps, or worse.
But this problem goes away if you just drop your need for doing something important. Nowadays, I don't care about the larger meaning of what I'm doing. I don't get hung up on that mental argument. I just take immense pleasure in the craft of producing software. Writing code is wonderful - you get to solve puzzles all day and learn new things. If that code changes the world, then great, but I don't 'need' it anymore.
- Pay - quitting Google cost me 1/2 a million dollars. I didn't make squat in my startup over the next 2.5 years. When I went looking for a job (I'm in Colorado), I realized that Google pays in the 90th percentile, and it was hard to find companies who would match my former salary.
So in retrospect, I probably would have stayed and just worked on side projects to satisfy my curiosity while I continued to make bank at my day job.
There are many, many wonderful things about Google - the people are all super smart and competent, the internal systems rock, HR 'just works', things like expense reports aren't a pain in the ass, and you can go off and explore awesome internal technologies.
Yes, you might spend some time working on 'boring' stuff, but that's going to be true at any job.
Anyway, that's just me, and I have a ton of perspective. I never would have found that perspective if I hadn't quit, so everyone has to follow their own journey.
Good luck.