For me, it's not so much about inVentiv... I felt pretty good about inVentiv, but it's all about the client company and your specific manager.
I have been on 3 contracts with inVentiv now. Two of which I reported to a client manager (field rides, etc.) and worked closely with "direct" reps. The other contract was a totally separate inVentiv team, inVentiv manager, etc. But all three were good and I never felt micro-managed. No one cared about signatures and it was really all about the sales results. With that said, you need to play the game a little bit. But if you're simply doing your job, you shouldn't have to worry much about all the other "stuff".
As far as any other differences in the job itself... I did the same job as I always did working for big pharma and worked just as hard. I probably felt the same pressure too. Unfortunately the pay is lower, less vacation, fewer perks and, yes, it could end at any time with no severance for cushion.