If you're playing the games chronologically, Final Fantasy IX marks a return to "normalcy" of sorts for the series. With its medieval-ish locations fused with elements sci-fi, a plot based around political intrigue (at first), it would seem the ninth entry was too same-y to stand out. However, IX improves on just about everything in the series and makes it one of the best.
The plot evolves to include the themes of identity and humanity first introduced in VII, while also featuring its own lunatic with ties to the main hero. The mechanics offer a more streamlined ability system, where you learn abilities from the equipment you select; buying the best of the best every time won't always be a wise idea, since you'll miss out on some vital abilities.
The characters themselves are a definite strong point. The cast is varied, ranging from a small boy to a disgruntled princess who wants to restore her mother and the stodgy knight with a shining heart who only wishes to fulfill his duty. Final Fantasy IX restores the earlier distinctions between characters in battle as well. Garnet is as delicate as you'd expect for a white mage, while Steiner is a powerhouse, and Quina is…well, Quina. Combined with the fact that the plot frequently forces you into situations where you only have certain party members available, it makes for a much more interesting and varied experience overall.
Plus, the game has one of the most unexpected and memorable opening sequences of any video game. At times, though, it can be a bit too easy, and the ATB meter seems to move excruciatingly slow sometimes, but these are minor issues on whole.