Although the vision of the company is extremely compelling, DS has missed every major technology shift of the last 20 years. The company is always playing catch up because it tries to compete at the wrong level. How could a company with great vision be so blind about it's place in the world of technology? Some examples (I swear all are true): DS once tried to "own the desktop". When CATIA ran on Mainframe and UNIX Workstations DS decided to build a better desktop experience than Microsoft. When browsers were born DS decided to develop a better browser. When social networking exploded DS decided it had to buy one of it's own. Now DS is late to cloud computing and online sales. I lay this issue squarely at the feet of the leader of the R&D team: Dominique Florack. Time after time he has been wrong and yet he still is in charge of the technical direction of the company.
The company organization is too complex and this leads to confusion among employees and unhealthy internal competition among mid-level managers. It takes years to assimilate new acquisitions. DS' array of business systems are confusing, irrationally assembled, and mostly built internally.
DS is a French company and there are real challenges to overcome if you don't understand French culture and "the DS Way".
In my view the Pros outweigh the Cons, but you do have to be able to tolerate some frustration. A lot of very smart people are still here because they, like DS, have a long term vision.