Pros
Depending on the team you get assigned to, the hours tend to be reasonable. Expect ~40 hour work weeks for most teams with a bit more depending on the team. This can vary depending on the team, but after several years of working at ServiceNow, weekend work was fortunately rare. Many teams use Scrum and there is a lot of maturity in their processes. Typically people self-assign work. The work can vary between development work, working on customer issues, and investigating and fixing bugs. Expect it to take a year to come up to speed and really get a good grasp of the product. The work is fairly interesting and the product itself is extremely flexible. The stock, while I was there doubled in value and bonuses were given out every 3 months. There was never a quarter where there wasn't a bonus. The gym in San Diego is pretty nice. They were good about providing the tools needed to do your job. Ask for a wide monitor.
Cons
After several years of working there I never received a raise (not even a cost of living increase) despite good reviews. I received no additional stock after the original offer. There was no indication from management above my boss that they thought I was valuable. In fact, getting 85% of your bonus is considered doing exactly what you should be doing. This means, that if they offer you 10% of your salary as a bonus, you should actually expect to receive 8.5%. Middle management on the development side comes across as unpleasant and I avoided contacting them when at all possible. While there are some middle managers that are easy to get along with, generally I did not want any interaction with them. The company in general is all about the stock price. Don't ask about 401k matching, they won't consider it (and will give you a lippy response). Unlike other places I've worked, they also don't seem particularly interested in talent retention. Beyond not giving raises/stock etc, they also don't have much in the way of groups to join, volunteer work, etc... You won't find groups for people of color, women, LGBT (though they did have a running group).