Pros
Thales has a lot of projects in the area of defence, satellites, business which usually are involved with public institutions but not only. In this sense, it is a mostly safe and stable workplace. Depending on the project you are working on, the tech stack might be somewhat old, as some projects are legacy and maintained. Although there are many opportunities with newer stacks. The pay rise is usually done yearly if everything went good on your side.
Cons
There is a lot of bureaucracy as it is a global and large scale company. If there is a need of some tools / configurations, the necessary approvals might take awhile due to this. So if you were in a dynamic environment, here you will find a totally different dynamic. There are many restrictions due to security reasons (in internal networks, on your working machine), so there will always be some bumps in the road due to this.