I think the chronon hunt is rather well done, it's not really hard to find them when you know you're supposed to look for them, and they sometimes add light puzzle elements. It actually makes the exploration phases much more interesting. And the timeline makes it easy to go back to levels where you missed one.
My only issue is that the game doesn't let you backtrack in a level, I have missed the same chronon twice because I assumed it was inside a building, but entering it triggered a new section and I couldn't get back outside where it appeared on my radar.
I thought they could have been better implemented. First it has you using your vision powers constantly, second a few of them are placed in areas you can't even access till a later stage, which just lends to wasting unnecessary time trying to figure out if you can or can't even get them. Lastly, the areas and arenas generally aren't even large or complex enough to really make exploring for them feel truly rewarding, instead most are fairly simply placed, even though the expectation is generally otherwise. I do however like that they are sometimes higher up, sticking to objects, walls etc. The effect from them is pretty cool too.