I also bought a couple of bottles of 1997 Castello Banfi Brunello di Montalcino while in Italy, paying way too much (as it turned out the wine was a lot cheaper in the U.S.). I still have one bottle.
I keep a database of notes on the wines in my cellar. Below is what Wine Spectator, Robert Parker, and Steve Tanzer have said about the wine. My impression of the first bottle was closer to Parker's assessment, which seems consistent with the majority of the posts on the Wine Advocate Bulletin Board. It's possible, however, that because of the huge production (32,500 bottles) that there's a lot of variation from bottle to bottle. In any case, your bottle should be ready -- assuming you've kept it properly (cool, relatively constant temperatures and out of the light).
Here are the experts' comments:
Wine Spectator, June 30, 2002, 94 Points: "A Brunello for everyone. Solid and focused, with mineral, blackberry and licorice character. Full-bodied and very chunky, with lots of round tannins and a long, long finish. Needs time to open. Best after 2003. 32,500 cases made. - JS"
Wine Spectator Top 100 Wines of 2002, Rank: No. 3
Wine Spectator, 12/15/07, 1997 Italy Retrospective: 94 Points. No notes.
Robert Parker, Wine Advocate #144, December 2002, 86 Points: "The internationally-styled, dark ruby/garnet-colored 1997 Brunello di Montalcino is somewhat one-dimensional, offering straightforward aromas of sweet new oak, black cherries, and currant fruit. In the mouth, it is medium-bodied and clean with a modest finish. There is sweet fruit, but little complexity, depth, or length. However, it is one of the finest wines this estate has yet produced. Drink it over the next decade. Drink 2002 - 2012"
Stephen Tanzer's International Wine Cellar: "97 out of 100...Very dark garnet with saturated purple hues. Penetrating aromas of underbrush, sweet tobacco and wild mushroom. Quite juicy, but also sumptuous and deep, with rich flavors of mocha, espresso and anise over a firm mineral backbone. There is no evidence of excess weight in spite of the wine generous structure. The long close features glossy tannins and a flavor of cassis. At once powerful and elegant. Among the largest producers in Montalcino, Castello Banfi is arguably the one making the best Brunellos today, with a remarkable string of successes since 1990."