Well, this movie was... Good? Yeah, I'll go with that. Good. Not great, not terrible. It's a little confusing, but I wouldn't say it's bad. I don't like a movie that forces me to take notes. To quote Decade, I understand the gist of what was going on in the movie. However, to fully understand things, I'd have to take notes and make sure I put everything together in a clear order of events. (WARNING! Incoming wall of text ahead...)
There's a lot of details that make it confusing. The opening moments made me think they were retelling the first few episodes of Zi-O, but they weren't. And they never tried to tie in that final scene from Kamen Rider Build's movie "Be The One", which was a trend since Ex-Aid at least, but oh well too bad. There was also conflicting details like how the Build Riders are still Riders with their memories intact, but the villain was using Den-O's time travel powers, which pretty much explains a lot. Two time altering powers competing with each other was a very interesting thing. It nearly overpowered Sougo and his personal friends, but thankfully they kept snapping out of it, probably because of their own Rider gear. (Like I've explained elsewhere, being a Rider that can alter time would be pointless if you didn't have gear that made you immune to timeline changes, and I'm pretty sure that's what the Rider gear from Zi-O does.)
Honestly, the only thing I can't even begin to explain is the whole "creating a reality where Riders don't exist" thing. I doubt an Imagine, a Singularity Point, and an over powered Time Jacker could really pull that off. They never fully explain it, they never explain if it applies to the Showa Era or not, and the two brothers grow up thinking Kamen Riders are STILL a fictional thing despite all those emotional declarations of "If we remember them, then they're real!" I do think Sougo/Zi-O having a meta moment where he somehow leaves the world of fiction and enters a reality where Kamen Riders are fake would make for a cool story. However, the meta narrative here is just ham-fisted and probably should have been left on the chopping block. You can still have this emotional story of two brothers and Kamen Riders being erased from history, just leave the meta stuff out. But while all of that is confusing, I'm not sure if it's bad or not. It's basically the creators giving a nod to all the fans who grew up with Kamen Rider, as well as long time fans that never gave up on the franchise. It's a nice to see that kind of acknowledgement, even if it's confusing.
But what I am disappointed with is how Zi-O got the Double Ride Watch. I knew it would be explained here, but it would have been nice to see SOMEONE from that TV show. Heck, they could've at least hired back one of Shotaro's informant characters from the show to be the ramen stand owner. That being said, there was a LOT to like about this movie too. It's good to see the playful banter between the Build Riders again; I always loved it. That moment between Momotaros and the original Ryutaro (Takeru Satoh) was such a heartwarming 4th wall breaker, because it is good to see him after tons of movies without him. Heck, the Den-O moments in this as a whole were a lot more bearable for once! (But despite how much his Imagin begged, I doubt we'll see them again after this.) Thanks to the recycled voice clips, I'm pretty sure the Hibiki in this was the original Hibiki and not his successor. But the best part was how they handeled Kuuga! Couldn't get his original actor? That's okay, just grab the power from the corpse of the original Kuuga from the ancient past! Best way to handle it, period. And while I'm not sure, as Sougo and Sento shared that final scene together before departing, I'm pretty sure Sougo's Zi-O powers were kicking back in. The Build Riders would soon lose their powers and memories again, but Sougo would still remember and still have the Ride Watches.
The villain was kind of lame, just going to throw that out there. Somethings I do wish happened but didn't: I wish we could have seen the Showa Riders. Yes, I know this is more about Heisei since it's the end of an era for them, and I respect that. Still, would have been nice to see a genuine All Riders moment. Maybe in the next Zi-O movie... Would have loved to see the Kuuga Armor in action outside of the Time Mazine. And I wish the CGI would get a little better, but that's just me.
Over all, I did have a fun time, though sometimes completely confused about what's happened. I know Kamen Rider movies have fallen out of the Director's Cut trend, but if any movie deserves it, I'd say it's this one. The confusing parts just make me feel like something is missing, and maybe 5 more minutes could smooth those plot hiccups out just a bit more. But let's face it, we all know why this movie was made. It's a parade showing off all the Heisei Riders. It's Zi-O, the last Heisei show, this was bound to happen. And even if you disagree, even if you feel like this was a waste of time or a waste of production, I guess we should all just remember what Owner from Den-O said... What's important is not the content, but what is remembered.