On a planet called Mobius, there exist seven 'chaos emeralds' which, when brought together, create a great magical power. Sonic's arch nemesis, Dr. Eggman, manages to gather the seven emeralds together, and creates a machine to utilize their power. He also captures two of Sonic's friends, Creme and Cheese.

With the help of his best friend Tails, Sonic storms into Eggman's fortress to rescue his friends. During his raid, Sonic ends up damaging the machine housing the chaos emeralds. The result is a phenomenon called 'chaos control.' Chaos control is a force that grants one the power to warp through time and space. The result: Sonic, several of his friends, and Dr. Eggman are teleported to the human world. Various bits and pieces of Mobius, including the seven emeralds, are brought there as well.

After arriving on Earth, Sonic stuns the world by effortlessly outrunning police cars and helicopters. Even the leader of the S-Team - a police force specially equipped with the fastest cars available - with his 'super nitro' is unable to keep up with Sonic.

Shortly thereafter, Sonic befriends a young human boy named Chris. Chris is naturally surprised to come across a talking hedgehog, and quickly begins to enjoy the endless thrills and adventures that abound around his new friend.

Sonic soon discovers that Eggman is also on Earth, and dead set on conquering it. It is also discovered that the seven emeralds have made it to Earth as well. Sonic and friends resume their rivalry with Eggman, and the fight for the seven emeralds begins once again.

This story is delightfully lighthearted - lots of action, but lots of humor as well. Some parts of the story follow the games (Sonic Adventure and Sonic Adventure 2), but most of it is new and original (so it's not just another shameless game-to-anime deal). There are a few episodes towards the end that are of less quality than the overall series, but you can count them on one hand. The ending was a little bit on the sad side, but it fits in well with the story, and does a nice job of setting up the events for season three.

Overall, the story is terrific. Well done.

The characters in the series are all awesome (although Big is definitely the weak link...). All of their traits are well-represented, and they are all very likable - yes, even Dr. Eggman.

Sonic's cool and carefree attitude is brilliantly expressed, and makes him an immediately lovable character. His super speed ability (he can run faster than the speed of sound) never ceases to be fun to watch, and contributes marvelously to some of the bigger fight scenes.

All of the characters are very well-developed and lovable. Creme and Cheese's innocence, Tails' and Chuck's brilliance, Amy's impulsive rage and complete obsession with Sonic, Knuckle's toughness and gullibility, Rouge's smugness, Eggman's fruitless maniacal genius ("Dr. Eggman certainly is a strategic genius." "I just wish some of his strategies worked occasionally." - Bocoe and Decoe), and Eggman's whiny, pessimistic, incompetent, often disloyal (I could go on, but I won't) henchmen are all brilliantly-expressed, and fit perfectly into the story.

The only real exception to this is Big the Cat. I mean, he's alright, but his role in the story feels very forced (except that he was in one of the games), and he doesn't quite exhibit the same lovable qualities as the other characters. Luckily he was only in a few episodes, so the damage was minimal.

The relationships in the story are also very well done. Early in the series, it seems that Amy is just an obsessed Sonic fangirl, but it is steadily revealed that she does, in fact, care deeply for him. Watching the more frivolous romance between Rouge and Kunckles develop is also very enjoyable.

So yeah, the characters are awesome. Although I have to say, the most lovable character of them all might have been Lucky. That little guy is adorable, and had me laughing out loud - particularly during episode forty-five. He's just so cute and funny and lucky that you can't help but fall in love with him...

This series is definitely worth re-watching. Even as we speak, I have a long list of moments in the series that I want to watch over again forming in my head. With so many comedic moments, all those brilliant fight scenes, and such a lovable cast of characters, this series has exceptionally high re-watch value. Not to mention how eager it makes you to watch season three...

The animation is excellent. The smoothness, color, and vibrancy of the series does a superb job of reflecting the frivolous and lighthearted nature of the series. The animation also does an excellent job of representing the delightfully fast-paced antics of the series.

The character motions are smooth well-animated, which does wonders for the series' countless brilliant fight scenes, and makes watching Sonic dash around all the more enjoyable.

The music is excellent (personally I liked the first opening a tad better than the second, but overall they were both good), and the sound effects throughout the series are excellent, and well-placed. Absolutely no complaints here whatsoever.

Ok, now for the voice acting. Lots of people absolutely despise the voices in the English version of the series, but I don't share their disgust. Yes, Tails' high-pitched voice took an episode or two to get used to. Yes, Knuckles does sound a tad Vegetta-ish - although that one is almost dismissible, seeing as how it does a good job of reflecting his tough-guy persona. Yes, the E-101 series robots tickled my 'battle androids should not have high squeaky voices' pet-peeve (which I first developed after listening to KOS-MOS in the second Xenosaga, by the way) a bit. All of these things are true, but I just don't get as mad about them as everyone else seems to.

I just don't feel that any of the problems listed above were that big of a deal. Tails high-pitched voice was a bit odd, but somehow it seemed to fit his character type. Knuckles did sound a bit Vegetta-ish, but it suited his tough-guy persona. The E-101s did have high-pitched voices, but that did a good job of keeping in toe with how the other, more frivolous, robots sounded. Also, it did a good job of upholding the lighthearted tone of the series.

Other than those three minor details, I thought the voice acting was pretty good. But if you don't agree I think we can all at least agree on this: considering how bad 4Kids usually is at selecting voice actors, the voice acting in Sonic X is truly in a league of its own.