Pros
Mozilla is full of smart folks who are willing to help each other out in a pinch. We all work together, if someone's very busy and there's stuff going on, others will offer to help. It's a *very* good environment for remote workers - 75% of my team is remote, so nobody has the feeling they missed something because they weren't "in the office". The bonuses are indeed real, and the salary itself is competitive.
Cons
The developers choose the technology they work on with very little input from the Systems team, so sometimes we have to manage something that's completely inappropriate to the technology involved. However, that's actually changing in 2012 - already in 2011 there were some changes that developers did not like at first, but appreciate that we can better support them. So we're doing more of that, and hopefully this con will go away.