My old launch PS4 would ramp up when playing a game after an hour or 2 and something like Deux ex after an hour would be on full fan mode. My slim doesnt even seem to make a fan noise lol, never heard it spin up at all. Maybe I need to try uncharted 4 to make sure but so far its pretty silent apart from the normal drive noises. It does look quite a bit smaller, and does look better in the flesh, i also prefer the power and eject buttons being an actual butter rather than sneeze and switch it on like the original PS4. Its also allowed me to free up an Ethernet port as it can use 5G wifi and on my virgin 200meg on the test it can vary between 90 and 150 Mbps download, upload maxed out an around 12 which is about normal for Virgin.
The controller feels better but my two are launch ones before the slight improvement they made a year or so ago. The LED shining through the top isnt distracting at all for me and does make it easy to see what its doing. Another difference is that the controller will use the USB when connected to the PS4 via a cable to reduce latency, previously if you connected it via USB it would still connect via Bluetooth.