Severance agreement arrived, need a second opinion - what worked for you?

My manager said the package is final, but the letter gives me time to review. There are 14 people counting on me, so I am trying to be careful. There is a non-disparagement clause. Did anyone negotiate and succeed?

Thanks for writing this out. I went through something close to it 10 months ago, and it settled down once I kept a simple log of every call and form.