I'm on Lamictal and it's working well for me so far. It is a slow taper, 25 mg every two weeks until 100 mg, then you can go up by 50 mg every two weeks. So it takes a while to work, but it's really good for the depressive phase. It's great for BP II, and it's approved I believe as an add-on med for BP I stabilization.
Topomax does get used for bipolar, but it causes major cognitive side effects in a lot of people, to the point of getting nicknamed "Dopamax".