Is it perfect? Nah, nothing in life truly is. Some of the cameos are way too brief, and the implied voiceover participation of certain famous Rider actors failed to materialize. Still, even considering that, it's one smashing piece of monster fighting cinema, and manages the task of not overstaying its welcome.
If you'd like a more detailed overview of the actual movie, fret not. Iga is on the case with both Spoiler & Spoiler Free reviews. If you have even the most passing interest in Japanese superheroes, you owe it to yourself to check out his site. He's been working hard on it lately, and it is really looking good!
I do want to comment, however, on something I have noticed both Toei and Tsuburaya Pro. (owners of the Ultra Brothers) excel at compared to the owners of American superheroes. Toei and Tsuburaya go out of their way to add mystique to their older characters and shows. Riders, Ultras, and Sentai all celebrate the past whenever the opportunity arises, and it is almost always treated with the utmost respect in its context. If Kamen Rider 1 or the original Ultraman shows up, you KNOW it's serious business. The new stuff is the primary focus, but neither company loses sight of the fact that there is still money to be made off what has come before.
In contrast, American superhero franchises seem perpetually in denial about their pasts. SUPERMAN RETURNS was billed as a continuation of a series, but ignored two installments of it. How many years were there between the two recent mutually-exclusive Hulk movies? How often have we heard folks badmouthing this or that adaptation because it didn't hew to their approved "vision"?
I'm generalizing, of course. There are Japanese hero projects that do the same thing (hello there, SHIN KAMEN RIDER), and American hero projects that seem practically giddy to jump hip-deep into their legacy. I just find the difference in the prevailing trends in two parallel genres interesting.
Back on topic, enjoy this promo for ALL RIDERS VS. DAISHOCKER :