This anime wins on bringing in hidden points in every arc it throws at you. It will give you a little story and, subliminally, throw a curveball at you; but the ball will fly past your head if you were not paying attention and this anime is all about remembering what you saw before as they do a lot of déjà vu in it. That is, unless you were, again, not paying attention.
Each arc you will see starts off with a pattern: you will see what will be a new main character, be thrown into their world and pretty much know this character inside out. It seems like each new addition to the cast is a fruitful one and different from the rest.
CAUTION: Next portion of the review contains a possible spoiler. Read at your own potential risk.
Then a sad tale or dilemma will unfold at the ending after their story is finished. For whatever reason, I had no idea why this happened as I do not recall, but it always did. Whether it be a character leaving the town, being injured or another thing, this would ultimately bring them to their demise; to appear in the next section of the anime, anyway.
This anime stands out a bit for throwing new main characters as you go, intrinsic to most anime, but this one always takes out the newly introduced character before the next arc begins. Rarely in a death scene, only in one I believe, the rest just temporarily phase out the character.
This makes for interesting story development as the main protagonist is always one-on-one with the next character. Only in rare instances did a new one make a return in the next arc or another one later. It made you ponder where they went off to.
One, in particular, shrouds herself from serving as the main new character until the ending, though she appears right off the bat and serves as a humorous recurring character; despite being the titular character. She makes use of this though as she has the most meaningful back-story.
Outside the character-in-character-out routine, there are a couple more main characters that eventually stand out in the story as it progresses, but start off as pretty generic and stale at first glance. Then again, what anime doesn't do character development that way?
This was not exactly the most helpful review as I have not seen this anime in a while, but I remembered just enough to maybe give you some useful information concerning your choice on watching it.
I just recall that each arc had a subliminal meaning that you had to pay attention to from the start to comprehend. That, every character held a significant meaning and that you should never shrug off a certain one; even for a second. And lastly, that the buildup to the ending is one of the better ones you will see.
If you have seen Clannad, Kanon will feel very welcoming to you as well. Featuring resplendent visuals, very detailed characters among other things, this anime will easily satisfy you. And, as someone whom appreciates the best that anime has to offer, Kanon will provide you with a story that you would not remember too fondly, but would not completely forget, either.
