Truly inspired.
First, Chrono Cross is my favorite game of all time. Even so, I don't believe it's the best game I've played. "Favorite" is different from "best," and that's why I didn't give it a perfect score.
Second, Chrono Cross is not Chrono Trigger. It has little connection to Trigger's story, does not deal with time travel, shares precious few characters, and has a very different combat system. To many, this seems to be enough justification to give Cross an abysmal score. This attitude is ridiculous and childish. Chrono Cross stands as a great achievement in its own right, whether or not it has any connection to a groundbreaking predecessor.
There are so many good things to say about this game that I'll make an effort to keep them succinct. The very best aspect of Chrono Cross, picked from its many, many strengths, simply must be its music. To me, it's not even in doubt that Cross features the greatest soundtrack ever in a game; its themes continue to ring in my ears a decade after I first played it.
Another significant achievement for Chrono Cross is its graphics. Obviously no game from the PS1 era can make a living on eye candy anymore, but on just about any standard, Chrono Cross remains a pretty game even today. Character designs manage to be bright and fun without taking any weight away from the story, and the environments are so vibrant and detailed that you'll find yourself not caring that it's relatively small.
The story is what really makes a great RPG, and Cross's story somehow manages to be both intimate and epic at the same time. Unfortunately it's also not the most accessible... much like Xenogears, you'll more than likely be confused as to what exactly is going on during your first play-through. Part of this is due to the fact that you're continually switching back and forth between two alternate dimensions of the same world (hence the "Cross" in the title). But occasional confusion aside, you'll find yourself making decisions in the storyline that can actually affect the outcome (there are quite a number of different endings), you'll find plot twists, you'll find clever/witty dialogue, and you'll find a philosophical take on the role of fate in our lives which sometimes tugs at the heartstrings. Finally, if you eventually get the quote unquote "real" ending, you'll also find that Chrono Cross has mastered the art of the satisfying ending. It manages to capture the feel of the game as a whole, make you think, and generally wraps things up in a supremely satisfying way.
Chrono Cross is also extremely innovative, which is something it rarely seems to get enough credit for. For one, there's a healing screen after every battle, which ends up saving endless extra navigating of menus. It was also one of the first major games to champion the end of random encounters in traditional RPGs, which is something that has since become standard practice. Best of all is a New Game+ mode that puts every other New Game+ mode in history to shame. Let me count the ways:
*You keep your level and all your non-unique equipment.
*You can only get all of the 40+ playable characters by playing through the game at least 3 times.
*There are special items and armor that are in very limited supply in each play-through, and you'll need multiple play-throughs to be at your strongest.
*Quite a number of different endings to get.
*There are optional bosses that aren't realistically beatable the first time through to keep things interesting the next time around.
*There's a fast-forward and a slow-motion button.
Let me say that again: there's a fast-forward and a slow-motion button in the New Game+ mode. These work on every screen except cinematics and loading screens. Are you bored with that dialogue, since you've heard it 50 times? Fast-forward! Think that spell looks cool? Slow-mo! Think your character is running too slow? Fast-forward! Why no other games have implemented this feature is beyond me.
Anyway, all that said, there are a few minor criticisms that I have. First, the combat system is really nothing too special. Things are very streamlined, and seem to be targeted towards the RPG newcomer. There's a system of opposing elements, and weak, medium, and strong attacks, but it's all very basic; there's less strategy involved than some people might lead you to believe. There's no more depth to be had than in, say, Final Fantasy 7. If you're looking for a traditional RPG with a great combat system, try Arc the Lad: Twilight of the Spirits, or one of the Grandia games.
Speaking of the combat system and catering to newcomers, that brings up another point: again like Final Fantasy 7, Chrono Cross is a pretty easy game. RPG vets will have no problem blowing through the game, especially if you take the time to collect the better weapons and items.
Cross also gets some flak for not having a traditional leveling-up system, but I have a hard time calling that a definite negative. Essentially, you're unable to level in Chrono Cross, as there's no such thing as "experience." You only get better by defeating bosses. The downside of course is that there's no real incentive for combat, but the upside is that you end up enjoying the story and the New Game+ mode without having to worry about mindlessly sitting around leveling.
Keep in mind that these criticisms aren't so much weaknesses, as they are things which simply don't shine quite as brightly as the music, story, and other aspects do. When you have a game as great as Chrono Cross, even above-average elements seem conspicuous for no other reason than they're not quite perfect. By no means should the combat system or the fact that leveling is done in a non-traditional way keep you from experiencing this masterpiece.
Overall, Chrono Cross stands as one of those rare games that people will still play decades after its release; one of the very best to come out of something of an RPG golden age. If you consider yourself an RPG fan, it would be absolutely criminal of you to miss out on Chrono Cross. It stands with Final Fantasy 7, Xenogears, Final Fantasy 10, and Chrono Trigger as one of the greatest RPGs ever released.
Truly, they don't make RPGs like they used to.