The time travel thing was unexpected but fairly interesting but towards the end I got very concerned because of where it was going. One thing I absolutely HATE when it comes to time travel (especially in a sequel) is when it undoes all the experiences and moments that we have spent all this time watching to get the same result in a different way than we experienced. It just doesn't sit right with me and annoys the heck out of me, almost to the point that I feel like I've wasted my time. That being said, they danced on the line and managed to not fall off on the wrong side.
From what I got form implications, almost everything played out exactly the same as what we saw in the series. The only difference being that he didn't meet Shoko which I thought would mess it all up but it seemed to work out similarly. On top of it all they end up getting their memories back and all making it out okay.
TLDR: It had a story trope that I was afraid they would mess up but ended up being better than most stories that use it.
