The best part of the old intro is when the song really kicks in and they start jumping through dimensional portals in time with the music. Very fluid, energetic, exciting.
The same portion in the new intro isn't coordinated with the music at all, just Star and Marco running in the very dull and mundane Goblin Dogs dimension alongside Kelly and Mina. It's probably the weakest part of the intro, over five seconds of nothing really going on.
The worst part is that Star's face is near-static for almost ten seconds during this time, just looking forward and smiling the whole time. It's even more egregious because Marco is constantly reacting to the things around them the whole time, throughout the whole intro.
I think another thing that hurts it is that all of the locations they're going to are recognizable to us by now, which just makes it seem even more disjointed.