The user interface, thats the only thing that pisses me off currently.
Rest works flawlessly

In order from most excited to least:

1. SSD
2. Raytracing
3. Adaptive triggers on controller
4. Haptic feedback on controller
5. Improved controller battery
6. Revamped user interface
7. Partial game downloads & installs
8. USB Type-C
9. 4K Blu-ray Player

The Revamped UI may be better than I expect but I'll have to see what they come up with because the PS4 UI is near perfect for me.

My only concern about SSD (which is great btw) is actual size, while they will get them cheap at cost for the parts, 2TB SSD isn't cheap. If it comes with 1 TB, well, my 1TB SSHD is mostly full most the time.

User interface improvements are the most important for me, speed of navigating the menus, customisation and stuff is always welcome. I expect the console to basically just be a revamped specs in reality because that's all we really need.

What is ray-tracing?

Fancy new tech for lighting/reflections.

Weirdly I've found minecraft is the best showcase for the tech, maybe because the geometry etc is so basic it emphasises how realistic and amazing the lighting is.

The "Adaptive triggers on controller" + "Haptic feedback on controller" sounds the best too me.

"Partial game downloads & installs" is gonna be pretty darn nice too.
(that way you can ignore multiplayer stuff, or maybe langauge packs/sound files, cutting down the install sizes).

They should just tell us now how tiny the SSD cache will be, so people can complain about the size and they can increase it before releasing it.

According to the Wired article "it will ditch the spinning hard drive". So it might not be a cache after all.

Shorter load times are impossible to argue with for me. That's the hands-down winner for most positive "new feature" for my taste. Runners-up include ray-tracing and even better controls.

Yeah, nothing announced about the PS4 so far to me really suggests more, in substance, than improved efficiency all-around, but frankly I'm a pretty conventional gamer in the technical sense, so that's really the main thing I'm looking for anyway. I don't need a lot of gimmicks.

A lot of it is standard stuff for a new gen, like better UI and HW. What I'm looking forward to is something that will affect the gaming experience, like the controller and the SSD. I can't wait to get my hands on the controller and test it out. See what the difference is between driving in water and across the road.

If they stop censoring games, that would be a good start. As long they don't, I don't care about the new features cuz I wouldn't buy it.