While I haven't done a lot of bass fishing in the winter on this side of the state (did most of my bass fishing out of Spokane), I can add a couple of things.
First, bass, especially smallies, can be pretty aggressive even in cold temperatures. I've caught smallmouth in water as cold as 37 degrees--- on crankbaits. The trick is to find the right area and moving fish (pre-pre-spawn).
While what Smalma says is accurate on the inability of bass to equalize the pressure when coming from the deep, I've found that it isn't such an issue when the water is cold. In Lake Roosevelt, we routinely caught smallies in 60 feet with no problems. The only caveat was that we didn't try to race them to the surface... just took it easy. Even in the summer when the bass move deep, it didn't seem to be a big deal there.
I've also caught largemouth through the ice, and I had a guide buddy at the Potholes who would routinely try to be the first person to catch a bass each year-- he usually managed it in January. He also would catch bass on Spooks by throwing up on the ice and then working the lure in the melt water close to shore.
The thing that's important in cold water is to find the warmest water in the lake because that's where the fish will be the most active. Then, unless you're fishing smallies, try to keep the speed down.
Keith