I've managed to sample the Schlafly Winter ESB, Goose Island Mild Winter, Sam Adams Chocolate Bock, Sam Adams Old Fezzwig Ale, Sam Adams Winter Ale, and the Sierra Nevada Celebration.

Most of them don't do much for me, but the Sierra Nevada Celebration is pretty OK. The only IPA of the group.

Sam Adams Chocolate Bock was pretty good if you're into that style.

The Goose Island Mild Winter was good.

Schlafly Winter didn't do much for me.

Sam Adams Winter Ale didn't impress me. Tasted like a really boring brown ale.

All of these reviews are amateur at best, so take it for what it is. I'm no expert, but I know what tastes good to me.