Originally released in 2000 on the original PlayStation, Final Fantasy IX initially had a muted reception. However, as time passed and the game was reappraised it found a new level of popularity for its story, setting and characters. In modern "Best of the Series" lists, Final Fantasy IX regularly swaps places with VI and VII as the best-regarded game in the entire series.
The new version of the game will feature somewhat sharper graphics and a revamped control interface. No release date has been set, given that Square don't usually announce these things too far in advance I'd be surprised if it was any later than the spring.
ETA: NeoGaf has a thread here showcasing some of the original concept art for FFIX and some of the original high-resolution renders of the backgrounds before they were downgraded for the PS1 version of the game. Well worth a look.