Kamen Rider W starts off extremely well, and moves from strength to strength through the first half of the series. Following a format of mini detective story 2-parters which are generally quite good, we see villains rise and develop in the shadows, with the villainous Sonozaki Family pulling the strings and Kirihiko Sudo marrying into the family and beginning to work his way up. The backstory of our heroes is gradually unfolded, and while Philip's is a little obvious it's compelling nonetheless. As the series moves on Kirihiko is ousted and the mysterious holder of the Weather memory whose sinister experiments set him up to become the most powerful villain of them all.
Well, then in my opinion Seasonal Rot
The greatest flaw of W is its mishandling of characters. Hidari Shoutarou, a young detective with a heart of gold, striving to be badass and live up to the memory of his Hard Boiled predecessor is more often an object of fun than awesome as the series goes on, which is a criminal misuse of talent. Meanwhile, the effeminate and overall boring
character of Philip is emphasized as being the real power behind W in a totally mind boggling development. The arc leading up to their biggest powerup is literally all about how Shoutarou is weak and Philip just has to accept that- despite the fact that Shoutarou is the more dedicated, compelling character, while Philip is a bit of a flighty asshole who repeatedly thinks of dumping Shoutarou in favour of someone who can give him better stats.
The latter third of the series also sees the tension that's been building for a while gradually subside. Weather works for most of the series to become a serious threat, only to be beaten by Terui's rather unconvincing upgrade, and then the true villain- the one that's been around from the start- finally gets slowly to work and reveals that basically nothing that's happened for the past 40 episodes mattered. And then in the very last two episodes another villain appears totally out of nowhere, almost as if they accidentally ended the series 2 episodes early and needed to fill time.
The first 30 episodes of W are
gold and any self respecting Toku fan should
look them out. But as the series winds down the standards drop, and it's a crying shame.