I would argue the gameplay falls short of revolutionary. Several parts are frustrating but 90% of the time it’s a decent balance of rewardingly challenging timing & platforming vs. “press X and just watch your character do the sickest flip, yo” dumb fun.
The killer tunes, kickass visuals (one of the best early cel shaded games), lighthearted but spunky lore and just overall vibe make it a genuine classic. If you’re on the fence about it opt for Jetset Radio Future, as its an entire console gen worth of polished vs. the original and imho the music is even better.