About the Backtracking, I (and millions of players) can said that, when is a obligatory bactracking, are a annoying resource to stretch out the game, like in Metal Gear 1, when you have to do it to recover the fucking sniper rifle; seriusly, there are someone who this kind of things likes fun?? REALLY???!!
Backtracking can be fun if they don't try to bog you down while doing so. In SotN, let's use this as an example, it doesn't take you long to backtrack in certain areas because either you know how to avoid the enemies/are familiar enough to take safe routes, or you are at a level/have enough abilities to make any obsticle a breeze. For example, you can backslide, double jump over enemies in your way, and might be strong enough to dispatch most with a single hit. That makes backtracking easier to swallow.
Now, when fighting is a chore(enemies are tanks), and sometimes you get locked into rooms where you have to clear them just to procede, that's where I'd find annoyance while backtracking. And this isn't just on the LoS series, as IGA did this in LoI and CoD too. To put that in an equivalent of JRPGs, that's like playing a game where the random encounters are high and running into monster after monster with each step WHILE retreading areas you already explored. Basically, backtracking's only as good as the developers allow you to have fun while doing it.