So, first episode of KR OOO is like totally bright, yet why that art museum reminds me of Board (from KR Blade) I would never know. And I totally get KR Kabuto vibes with the motorbikes.
Don't care much for the OP. But then I never really like when they talk (instead of sing) in songs. (Could also be that I'm spoiled by the last two KR OPs, which I like a lot.) It could still grow on me, though, particularly the later parts, which seem to be remarkably free of rapping...
The main character doesn't seem similar to the ones from recent Kamen Rider series, which is good, because I like varieties. (Still can't really pin him down though, not at just one episode.) And I didn't realize before that I kind of missed the whole hero having to learn (at least a little) how to be a rider (last time I saw that in the first episode was back in KR Den-O, I think).
I usually have short memory about advance press stuff (I've read a little for OOO (or however I could shorten this) though), preferring to find out about the characters as I watch the show instead. So, well, I admit I had no idea whether the main character will be going by his first or last name. But as soon as I hear the girl (little sister of the policeman whose name I never caught, but apparently it would not matter since he's no longer himself) being called "Hina" by her friends it's pretty much settled for me that the main guy must be called "Eiji" by the majority (if not all) of the cast. (Because too similar names would just be confusing, I think. And the name Hino (sound-wise) almost always reminds me of Sailor Mars...)
As for other observations, most likely other people have already addressed them (and better than I could). I'll say it keeps me intrigued enough to tune in next time (but probably will wait for subs), although I don't know about long term (I still miss W, I suppose). However, if I manage to stick with this show, I don't really see myself talking about it regularly (but then so far I never posted about any KR series regularly, perhaps except Den-O).