I actually felt the opposite.
Both games have padding issues, which is what happens when you stretch one game into 3. But it bothered me a lot more in Rebirth. I think it's mostly because the game is much longer. According to How long to beat, the main story alone is about 48 hours as opposed to 32 for Remake.
I probably would have enjoyed it more if I had just decided straight from the beginning to just plow right ahead through the story. But, because I did like Remake alot, I was taking my time. By the time I got bored and stopped doing sidequests I still had like 20 hours to go. I think Remake was also more linear, which is in this case a good thing. An open world is great if you actually have a good open world. But, if you don't, it's just kind of in the way.
There are parts of Rebirth that are really great. Temple of the Ancients was a really amazing segment that almost saved the experience for me. And some of the side stuff is really good. But, at other times, it feels like they're just speed bumps to slow the story progression. Like, when Cloud finally returns to his childhood home, that is not the time I want to roll around and throw boxes with Cait Sith.
We'll see if you change your mind, because I was also really enjoying it for the first 20 hours or so. But that last 20... man it was a slog. This was one game split into 3, and it really feels like it. Remake was a great 20 hour game, but the problem is that it was about 40 hours. Rebirth is also a great 20 hour game, but the problem is it's 60 hours.