I agree largely with the above.

The real underperformers are:

Grosjean - I thought he would have been on Kimis tail, but it appears he is maybe to worried about his incidents last year and maybe he has lost that spark.

Perez - As said he really hasn't shown much to prove he deserved this drive over Hulkenberg and the likes. He has been behind Jenson and appears to be generally struggling.

Maldonado - The car is a real dog, but he hasn't really looked like team leader and Bottas has outperformed him at times.

As expected:
Bottas - As said above he is doing a decent job but the car is terrible.

Chilton - I think Max was expected to struggle and certainly to be behind Bianchi. So really he is working hard and not making the mistakes the Caterham drivers are.

Overperforming:

Bianchi - He really has caught everyones attention and in doing a sort of Alonso in a Minardi job.