Got my PS4 on Friday and I really like it. Nice solid little machine (way bigger than I was expecting which means the XB1 must be gigantic according to comparison photos), and aside from some PSN issues which lasted until Sunday, everything has 'just worked'.
Highlights:
Graphics are really amazing - I've been playing Assassins Creed IV, they 1080P patched it, and wow it looks nice.
Share button streaming to Twitch was dead easy and seems to be reasonable quality-wise. They need to get the upload updated to support Youtube though because Facebook sucks. I refuse to get a FB account.
Being able to play before it's finished installing is nice.
The UI is fantastic - no sh*t all over the place.
It's quiet - not sure why there were lots of dismayed posts about both machines, it's certainly quieter than a 360 and I thought those were fine.
I see from comparisons finally being posted, the graphics advantage is making itself very obvious already.