I'm about 3 hours in also and I agree with everything Naznatips has said. I've played Halo, Halo 2, Prime, and Prime 2 so I should be qualified to agree.
The best thing about the adventure/exploration part is they improved the scanning system. I think one of the biggest drags while exploring in Prime 1 & 2 was having to stop to slowly aim you scanner with the joystick everytime you needed or wanted to scan something, which was a lot of course. Now you scan by pointing and you can do it while running. It works much much faster.







