Anecdote from past experience: Last year I worked at a successful startup, seeing it through an acquisition by a Fortune 50 company. At first, the startup was great… it pushed its employees to their very limits and shipped some pretty cool software. But one-by-one, the employees could not take it any longer, and pretty much the entire original team is gone. In its now almost 5 years of existence, very few people stayed for more than a year.
Personally, I'm a pretty good developer. I've done some very cool shit, and I love what I do. But if you expect me to be all work and no play, the quality of my work is going to start to decline very quickly, and I'm going to stop having fun and quit very soon. I live by the motto "work hard, play harder." I have no problem fixing the servers on a weekend, or staying at work late. But if you expect me to consistently work more than is fair, or are gonna give me shit for arrive late or leaving early, then it's not gonna work out.