Yesterday I watched "Zen: Vendetta" and praised it. Something I failed to mention was that the mystery itself was a bit strange, in fact verging on preposterous ... but it was too enjoyable to complain. I've now watched the two movies that followed, "Zen: Cabal" and "Zen: Ratking," and now I know why the series didn't last any longer.
Yes, Aurelio Zen is a wonderful character, and the characters are well drawn. But the mysteries are incredibly poor: "Cabal" in particular made "Vendetta" look well thought out and sane. The other significant stumbling block to the entire series is that Zen, while very smart, only succeeds through extraordinary, in fact extraordinarily improbable, luck. Buckets of it.
Good characters, but because of the multiple other failings I'd recommend anyone interested watch "Zen: Vendetta" and stop there.