1. no hope for career. Job description is one thing, but when you joined, manager can move you to anywhere without notification. Interviewed for developer and you will be thrown to boring customer services. Even you complained away your career plan, no one cares.
2. Bonus doesn't depend on your behavior or performance. Only rely on if manager likes you or not.
3. Internal transfer is very unlikely. Once your manager knows you wanna move. last year's bonus will be much less than others. And no promotion or salary increase no matter how hard you worked last year.
4. Gradually, have to worry about what to do next week. Cause manager pushes you everyday to do billable tasks and push yourself to find it.
5. It is said flexible working hours, but someday your manager may check if your in-office hours is enough or not. Even you work a lot at home.
6. Productivity and budget will be the words you hate most. That's the excuse management use to everything including all above points.