In terms of fan noise, I'm definitely hearing the fan ramp up quite significantly in every game so far. Flower and Resogun make it ramp up as much as Killzone and Knack for me.
The only thing I have it to compare to is my 80GB non-slim PS3. In game, the fan is almost as loud as the PS3 is sitting on the XMB for 5-10 minutes. Reasonably audible, but not sounding like a plane taking off. The top of my PS4 on the non-glossy side is warm to the touch, but the strange thing is the fan is blowing out cool air out the back, like the air isn't hot as all.
Is this normal? I figure every PS4 is going to ramp up and sound a bit different, based on placement and how far back everyone is sitting, but a few people in here have been saying they don't hear the fan kick in at all during gaming sessions, and I can't see how that's at allpossible unless they have a defective fan and a console that is overheating.