It is a sweet wine - but not a swap-out for dessert like Sauternes might be.
It often has a steely salinity not unlike Sherry - but you won't mistake it for Sherry.
And Madeira is basically indestructible - you can leave a bottle open for years and it will never go bad.
Madeira is a fortified wine that is also subject to a heating process (which accounts for the indestructibility) made from indigenous grapes called Sercial, Verdelho, Boal and Malvasia, plus the workhorse grape Tinta Negra Mole, blended or alone. Named for the island from which it comes, Madeira is made in a range of styles ranging from drier to sweeter, usually seen in association with those different grapes.
I recently sampled a number of Madeira wines that showcased the range of possibilities you can find from these wines. Some favorites included:
The Henriques & Henriques Rainwater had a light gold color - at three years old, it was one of the babies at the tasting. It had a nice buttery element, both in texture and somewhat in flavor, with a hint of saline. The Rainwater designation refers to a lighter style of Madeira that is more approachable and the H&H showcased that beautifully. ~$18
My favorite offering at the Blandy's table was the Blandy's Colheita Malmsey 1994. A light mahogany color, it showed nice elements of floral perfume on the nose in addition to more traditional notes of caramel and sweet oak. It was rich and nicely balanced. ~$48/500ml
The star of the tasting, in my opinion, was the D'Oliveira Verhelho 1912. Granted, most of the tasting's offerings were more common and/or recent vintages, so there were not a lot of Madeiras at this level to compare. But I have a bottle of 1898 Blandy's Reserve Terrantez (a rare "fifth" grape) open at home which is pretty darn tasty, so I have some experience with long-aged Madeiras. The D'Oliveira had the most incredible nose of lilac. The florals in the mouth combined with a toasty caramel and lots of acidity. Just a beautiful wine. ~$400
So don't be afraid to give Madeira a try. The lighter and less-sweet styles - Sercial and Verdelho - are lovely as an aperitif, and the sweeter styles - Boal and Malmsey - will go beautifully with dark chocolate cake. In fact, adventurous Wineaux should have a lot of fun coming up with interesting food pairings for Madeira. And don't let the price scare you away; a glass once a year at a special occasion will make the bottle last and last, giving you a very hedonistic bang-for-the-buck!