I don't know, when I saw photos of the new Hulk now that it's completed, it looks exactly like the old track. At least from what I recognize of the first part of the track before it goes to the other side. So, unless it changes once it runs to the other side of the building, it's the same track. Which if that's the case, what's the point?
As for me the most overrated is RRR. It gives me a headache and it doesn't even bang my head around. Also, how it makes me feel in general takes away from the experience. So, now that I recently rode it for the first time in awhile, I think I'm not going on it again unless I ever go with friends who
need to go on it. I can kind of see the popularity of it all, as it's a massive tall coaster and one of the few at Universal, but it's subpar compared to the other coasters in my opinion. Also, it gives you two seconds to choose a song. I selected classic rock and when I didn't pick in time it did some dubsteb song.

Can't even pick a song in my category?
As for underrated, I do not know, there are a lot of rides that might fall into that category, but one of my favorites is Men in Black. I love the film, love the ride concept, and found out recently apparently the design for it and the idea of the ride is first to pose as it being something from the World's Fair of 64'-65', which I've always been fascinated by due to that fair's history also with Disney, which I'm also a fan of.
Some of you probably knew that little bit of trivia, but I only rode it once in the normal queue years ago (which is typically how you get the storyline) and every time since then I've been practically always riding it in the single rider line (which you typically do not).
EDIT- YES, THE HIPPOGRIFF. I AGREE. THAT MIGHT BE WAY UP THERE WITH RRR AS AN OVERRATED RIDE. I mean, why would people want to wait 90 minutes for a ride that is literally a minute long? I seriously have looked up the time and it's a minute. But then again, when you have little children, you might not have a choice.