I got my 360s last night and hooked it up. I see two issues with it.
First, the vent that allows the Xbox to blow out hot air is on top. Yes, right on the top of the machine. Everyone I know has put a game on top the of Xbox at some time or another. Blocking this vent will definitely cause the Slim to overheat plus the air blowing out of it is very hot. I don't mean really warm like the Elite but hot.
Second, the fan itself. Now my 16 year old daughter has a Slim and she has it on a wood stand, so I never noticed this but...my stand is glass. When the fan kicks on it makes a horrible noise because of the vibration. It sounded like a buzzer was going off in another room. I need to figure out a way to dampen the vibration noise. It's really obnoxious.
All and all a cool system. Now my PS3 and Xbox match.
I have another problem but this is with Microsoft's policy. So I had sent my Elite in to be repaired and rather than do that, they sent me a new one. They transferred my game licenses to the new Elite. The Elite was the central Xbox in the house but now that we have a Slim, the Slim needs to be the central Xbox. 95% of all DLC and games are downloaded under my gamertag and on the Elite. I cannot transfer licenses to the new Slim because Microsoft took it upon themselves to do transfer them to the new system they sent me. This means no one can play DLC or downloaded games unless they either play in my room or I have to be signed in on the Slim while they play. I am trying to get Microsoft to see the error and release the licenses so I can transfer them. They have a 'One transfer a year' policy. I am screwed until January if I can't get them to see reason.