Pros
The expense allowance policy can be attractive depending on the client/project location. Opportunity to work with large industrial clients and gain exposure to relevant technical environments. In my case, the day-to-day experience with the client (Bosch) was positive and professionally enriching.
Cons
Very limited connection with the parent company. Most of the time, consultants feel detached from ALTEN itself and integrated only with the client. Consultants are often treated more as allocation resources than long-term employees. Internal communication and contractual formalization processes can be unclear and inconsistent. Project transitions and compensation discussions are not always handled transparently and, as in my case, may result in consultants accepting a new project based on revised compensation conditions that are later not formally implemented.