Smooth, clean, and rather rich, with a depth of malt character. This is one of the classic malty styles, with a maltiness that is often described as soft, complex, and elegant but never cloying.
Domestic German versions tend to be golden, like a strong Pils-dominated Helles. Export German versions are typically orange-amber in color, and have a distinctive toasty malt character. German beer tax law limits the OG of the style at 14°P since it is a vollbier, although American versions can be stronger. "Fest" type beers are special occasion beers that are usually stronger than their everyday counterparts.
Paulaner Oktoberfest, Ayinger Oktoberfest-Märzen, Hacker-Pschorr Original Oktoberfest, Hofbräu Oktoberfest, Victory Festbier, Great Lakes Oktoberfest, Spaten Oktoberfest, Capital Oktoberfest, Gordon Biersch Märzen, Goose Island Oktoberfest, Samuel Adams Oktoberfest (a bit unusual in its late hopping)
You can view the complete style details on the BJCP website. The 2008 style guide is obsolete but there is a similar 2015 style that you can view below...