Does Final Fantasy IX still hold up for a first-timer?

Holds up really well, better than most of that era. The story and the cast do the heavy lifting. What bugs first-timers is the pace: random encounters are frequent and battles are slow, and trance fills on its own so it sometimes kicks in right as a fight ends. The modern ports have a speed-up booster, use it and the game feels fine. I'd leave the no-encounters one off for a good while or you'll end up underlevelled.