Mark,
I played this course for my one and only time in 2003, but found it to be underrated. TCC and Salem and Kittansett get all the press in the Boston area due to their histories of Opens and Ryder and Walker cups, but there is a very solid Division 1-AA that includes Winchester, Charles River, and Brae Burn (although BB is arguably at back end of 1-A).
Winchester is a great design on a very severe site that honestly doesn't feel that way when you are playing it. The back nine is built on the side of a large hill, but plays relatively flat. One must remember the slope, as it effects putts on the greens built into the hill. Many of these Mass. courses are used to great effect in local amateur and NEPGA events, but wouldn't challenge the pros too much.
As far as the TCC comparison goes, Winchester lacks the history and the ambiance of the clubhouse area, and old-time routing of TCC, but its course is definately more interesting than the regular 18 at TCC. I've never played or walked the composite, as that is probably one of the toughest tests in the region, but Winchester would hold up pretty well even in that match I would think.