I won't recommend going for GEES unless you are desperate. Not sure about Petronas GEES but my experience in another company is that we treat GEES as cheap labour and fulfilling our "duty" at the same time. We only hire them after the period ends if they have outstanding performance. YMMV with Petronas though.

If your GPA is good, best to try to keep applying for proper job as its both more secure, higher pay and you have a purpose in a specific position in the company.

EDIT: That being said, most GEES participants do get good job exposure...if your up for the experience it could be worth.

I believe GEES program's objective is to increase a person's 'employability' in future. Putting this 12 months working period into your resume would be more attractive to future employer instead of just indicating you are fresh grad.

Even if you excelled outstandingly during GEES, your superior still can't take you in as permanent staff unless coincidentally there's an open position at that time. If there's no open position, the superior has to justify/present at so many levels just to take you in.

If I were you, I'd try to get more information on which Petronas company you were offered. E.g. design, refinery operations, exploration, etc. Find out if is this your field of interest.