I honestly don't know what to think of Chronicles. It's a great idea to have side-stories on secondary characters that we don't get in the main series, and it would've been nice if they had kept this going in later seasons. However, what was good about the series tended to be overshadowed a bit by the bad, and that nearly ruins Chronicles for me. It shouldn't be one of the negative reasons, but the dub is just awful here, and it's distracting. It's odd how 4KIDS slipped on this one—it's probably understandable given the circumstances at the time, but I can't think of anything of the dub of the main Pokémon was terribly written. (But I have of yet to check out the Hoenn episodes at this time. There probably was a difference between Johto and Hoenn in that regard.) Even the voice-acting was a step down from the main series, but I've complained about that before, so I'm not going back into it.
Another thing I didn't like was that the stories—the meat and potatoes of the series—sometimes fell short of the potential they set up in the beginning. The only real good ones I personally liked was “A Family That Battles Together, Stays Together” and "Legend of Thunder", and possibly “Training Daze” for delving more into Team Rocket's past, but I feel like that one retconned something or whatnot. The one episode that made me mad and has to be my least favorite was “Celebi & Joy” for the way it handled changing the past and changing the future without any negative repercussions (never mind the fact Celebi itself barely appears). It apparently only changed the future for that one town, but how do we know the rest of the world hadn't been changed, particularly with Ritchie himself? Time travel is hard to write correctly, I get it, especially for a twenty-minute episode, it's just pretty bad when Pokémon 4Ever did time travel better even though it's one of the weaker movies. (This is more nitpicky than anything else, considering time restraints may have been the biggest issues.) Really, some of the things that were shown to have changed in the future didn't make sense to me. How do we know Nick would've ended up being mayor had he lived? Who was the mayor to begin with before the change? Why didn't he make an appearance, even if only for a scene so we could feel more satisfied with the changes? Why bother to save/renovate an old Pokémon Center? What, the original mayor wasn't going to bother building a new one in its place? Why villainize a character we know zilch about?
Other than that, the other episodes were either missed opportunities (“The Blue Badge of Courage”), boring (“Those Darn Electabuzz!”), or forgettable (“A Date with Delcatty”).
Still, despite all of its problems, I cannot deny that Chronicles was a fresh entry even if the debate of it being canon or not seems to be a thing in the fandom. While Ash was never a main character in this series, his absence didn't take away from the rest of the cast that were featured, giving them a chance to stand on their own. Some of the characters had more screentime than others (whether they really needed it or not), but while some of the characters I personally didn't care for, they pleased other people, and that makes Chronicles a personal preference than anything. The characters kind of had development in some areas, but most of the time they were the same as when we first met them—Ritchie and Casey being the worst offenders to me, not counting Butch and Cassidy who were actually regressed as characters to fit Jessie, James and Meowth's roles. I don't think anyone really “grew”, to be frank.
Do I regret watching the series? Well, it's not a rewatchable series in my opinion, just something there on the side in case you're curious enough to take a look before moving on. And because it's more of an optional series and not so much a “must see”, it's kind of a waste of time with some of the episodes nearly intolerable to watch dubbed. As a Pokémon fan, however, I would like to see as much of the anime as possible, even if only to say I have seen it. It didn't take away anything, but it didn't really add much either. And that is more disappointing to me than it is frustrating.