I won't say much as most had been covered by previous candidates.
The only thing that I liked the most was the in-person technical interview, no bs questions like "where do you see yourself in x years type questions", a good 3 hours of routing and switching questions and a little bit of security and firewall. If you have a strong foundation of CCNA R/S and Security topics, you will nail this interview.
What would have made me decline their offer is not the salary entirely, but their hiring process and possibly how the TAC managers treat their teams here in the Americas (read other reviews). They were some red flags early in the process, the hiring managers there in Plano have worst to zero communication skills, you will need to send 2-3 emails before they can respond to you. It took them weeks to make their decision after all interviews and stuff. (Looks like a good number of folks had the same experience)
This had to be the worst hiring process I have ever experienced in my career. If you can't show respect to your soon to become team members, no one will want to work for you period - you are leaving a negative impression of your hiring practices. However, kudos to the guy who conducted the technical interview.
What need to be done: someone in the upper HR will need to review this hiring process before things go out of hand. We were really surprised by the hiring process of a big company like Fortinet.