After Install the iMac Was at Full Brightness Level

Hi. After installling Mountain Lion, the iMac's (late 2009 model, batch March 2010) brightness level was set to full. Is this the ergonomic brightness that Apple recommends for the iMac with LEDs?

What other changes from Lion did Mountain Lion perform after installation (must check so it doesn't cause problems overtime)? Does it change the PRAM settings or the SMC?

Thank you in advance.

Gbu.