Interesting. My initial reaction was: it's fine if you stick with the core, and end the campaigns around 10th level or so. I ran a 3.5 game for about 2.5 years, and the players didn't get past level 9, and it was fine. Likewise, I played in a Dragonlance 3.5 game for about 5 years, and didn't stray far from the core (we had a couple class variants from the 3e Unearthed Arcana mixed, plus a couple DL specific classes), and we tapped out around 11th.
Overall, 3/3.5 was a solid system, and I had fun with it, but again, I wasn't stirring in 20 different sourcebooks.