I'm watching it right now, and I'd say it's pretty darn good. It's not exactly a typical rider series though, so if you're expecting something like Fourze or OOO, then you'll probably be rather bored by it. And if Switchblade is to be believed, don't watch past episode 29. You'll only get Inoue'd.

So it's a serious Rider?

And... I might regret asking this. But what is Inoue'd?

It means the series is gonna get fked up bad.

I don't doubt that.
But then again, I'm hard pressed to find a series (Other than Decade) that I wouldn't call good...

Agito definitely had a unique flare to it. And it's connection to Kuuga (and inversion of its premise) make it so interesting.

That's actually the biggest reason why I haven't watched Agito.
I really have no want to watch Kuuga right now, and because I've heard about how Agito is something of a continuation, I feel the need to watch Kuuga first...

It's not really a continuation, they just have some connections.

Did someone mention Hibiki?

Unleash the rampant praise and Inoue-bashing! :D

The first 29 episodes are the single best Kamen Rider series of the entire Heisei era, if not of all time.

It's serious but it has its lighthearted moments. It's not goofy like Den-O, but it's not a melodrama like 555.

As for the Inoue thing...

Hibiki is a fantastic show, absolutely fantastic. But the toy sales were crap and all the location filming burned through its budget really quickly. Toei wanted the producers and writers to do some overhauls to make it cheaper and more marketable. They refused, so Toei fired them and brought in Toshiki Inoue, the head writer for Agito and 555. The result was... well, objectively speaking the result was a really generic last 19 episodes with reduced characterization, blander monster designs, and a lot more stock city locations. Subjectively, it was the worst tragedy in the history of tokusatsu. A horrible new character was brought in to add drama, the show's fantastic score was replaced, the new villains made no sense and were ridiculously goofy, two episodes were devoted solely to proving that women are too crazy to be Kamen Riders, and the ending was so slapdash it was literally being written while they were filming it.

Technically, the show's ratings improved, but from a PR standpoint it was a disaster. The cast was incredibly and vocally unhappy with what was happening, as were the show's fans. Toei got a lot of egg on their faces over what happened, but not enough to bother undoing any of the changes. By then Hibiki was basically just something to finish burning off until Kabuto was ready to launch. It was a disastrous ending, but you shouldn't let that discourage you from watching the real 29 episodes, which are a fantastic blend of strong characters and character-driven stories, beautiful outdoor locations, unique cinematography, dodgy CGI, and the lovely Mayu Gamou.

And if you like it, it's always worth checking out Daimajin Kanon, a show from 2010 that reunited much of Hibiki's production staff. It's a completely different show, but there's a lot of Hibiki still left in its overall tone (I've also seen it argued that Daimajin Kanon is an allegory for the production troubles of Hibiki, which actually makes sense when you break it down).

(sorry, Sentai, but Switchblade is to Hibiki as you are to Goseiger)

(except my show's good :p)

I'm currently keeping up with Wizard. Also, I started OOO a long time ago but haven't really gotten to finishing it. They're both great, though.

They are connected. It takes place 2 years after Kuuga and the G3 System was developed as a means to combat the Grongi if they ever returned. However the Unkown (or Lords) are the creatures that begin to attack humanity which is also wen Agito and Gills appear.