shadow fall was an amazing shooter, and took a step away from what it normally did in the series, while keeping everything that made killzone, killzone. The open levels, the different styles of play encouraged, the variety in environments, the amazing guns (with a return of secondary fires). Plus the owl. And the story was great. Maybe not as epic as killzone 3 or 2, but shadow fall's supposed to be like a good hop-on point for people new to the series. It's also a way better shooter than battlefield.
And there's not much restrictions in second son, I'm not sure what you mean by that. You can actually fall in water and not die now. You can traverse way easier. Plus you can have more than two types of powers, which was KIND OF the limit in infamous 2 (I say kind of because it was really more like 1.5 types of powers). There isn't as much variety in powers, i'll admit, but like you said, delsin's a new character and not really established yet. I see it as like any origin story.