I have been wondering why I do not see people mention the speed of the interface more when talking about these next gen consoles. My PS3 still gets a great deal of use because I have such a backlog of games. The one thing that bothers me every time I go back to my PS3 is just how slow it is compared to the PS4. I absolutely love how fast the new system is. It seems as if I am never waiting for anything unlike the the older model. I really noticed how irritating it was just recently when I went to watch Netflix on my oldest PS3 that does not get as much use and had multiple updates to endure. I think it was at least 5 minutes before I actually got to stream a movie.
The store is absolutely fantastic to deal with now. I used to hate going to the Playstation store just because it seemed so damn slow. Of course it is all amplified now that I have experience with the PS4 interface. Oh, and yeah, the trophy sync always seemed just insanely slow to me and I never understood that.
Now, I turn on my PS4 and everything is taken care of and I go about my business while it does something in the background. For this reason alone I look forward to the day that I use it exclusively.
As far as game progression, it will come. I just went back and played Assassin's Creed II after playing Assassin's Creed III for the first time. I could not believe how bad AC II looked by comparison. It really put into perspective how far the PS3 had come. I am sure the same thing will happen this gen.