I worked in banking and a few startups before joining Mozilla, and neither the culture or technology were ever great. Mozilla has both of these things, and a mission statement that still makes me want to get out of bed in the morning (work for mankind, not for the man).
Is it a sinking ship? Only if we're not up for the challenge of fighting back corporations that want to lock the web being walled gardens. Time will tell, but someone should fight the good fight, even if it's a lost cause.
Plus, you get cool t-shirts, and work from home, which is definitely a lifestyle improvement for me.