Pluspunten
Teams are great: young and international, everyone comes from a different background, and a lot have a passion for tech. Sushi pizza Fridays, pool table, video games etc. What you should expect from a tech company. Criteo also keeps up with new tech (not always at it seems though), for example adapting its CPC model to a CPA model in order to suit advertiser's needs.
Minpunten
As the company is expending very fast, some decision can be slower to take, and everything new tech seems to be taking quite a while to be implemented. For example mobile is an area that a lot feel is exploding, yet Criteo seemed not to be dedicating lots of efforts in it a few months ago (things might have changed). Another point is that during my period there, a lot of management was hired directly from Yahoo, to leave afterwards, which certainly sent the wrong message to employees.